The perilous world of online reputation management remains big news. Scare stories about people being sacked due to objectionable online content abound, with The Guardian reporting that more than 1,700 people have been sacked or disciplined for Internet misuse in the past three years.

What's considered far less is the risk in not having any kind of presence online. Total online anonymity may be the ultimate protection from harm, but it's also protection from opportunity. A personal website, a few Google results and a LinkedIn profile are no longer just helpful – they're expected. Without such a presence, you're suggesting that you're unable to make any kind of mark.

More and more, we're finding that first impressions are made online. HR departments want to find out more about you than your CV lets on, and the Internet provides an invaluable free resource in this search. This isn't a work-only activity, either; we've caught ourselves Googling people that we've just met to assess whether we're socially compatible long before we would traditionally find out the information face to face.

It's easy to find you

Social-networking sites can provide a great deal of positive exposure. They're highly respected by search engines due to their link-heavy structures, so they'll quickly appear in the first page of search results. Google will generally be the first port of call for anyone looking for your information. It's therefore paramount that you take control of your own search results and transform that first page into a portal to your online existence.

The two most useful social-networking tools around today are LinkedIn and Facebook. The two sites are like chalk and cheese, and each serves a very different purpose. Facebook provides friends with a way to share photos, play games against each other and arrange social events.

By contrast, LinkedIn shuns the term 'social network', describing itself as a 'knowledge network for professionals'. Humour, party photos and rambling monologues are contraband; dated job histories and carefully crafted personal profiles encouraged. With a global membership of 28 million and a year-on-year growth rate of 361 per cent (according to market research company Nielsen), if you haven't joined yet then you're already behind.

LinkedIn – your poker face

Your LinkedIn profile should fall somewhere between a business card and a full-blown CV. Unlike a Facebook profile, you can't capture the interest of passing contacts by listing your favourite films; you'll get little attention unless you're able to offer your visitors a valuable service.

It's important to have a complete and up-to-date profile. To help you achieve this, the site displays a percentage representing how complete your profile is as well as tips on how to improve it. It's made so easy for you that it's painfully apparent to those browsing your profile when information is missing. It's a far subtler path to failure than writing about your toenail collection, but an incomplete profile could easily give the impression that your personal management skills are lacking.

It's a good idea to add as many contacts as you can in order to expand your searchable network. When you search for a name via LinkedIn, you're only able to view users that have up to three degrees of separation from you (friends of friends of friends). The more contacts you add, the larger your searchable pool will grow. It'll also help if you decide to look for jobs in your area of expertise.

LinkedIn enables employers to advertise positions through the site, and if you have any degree of separation with the employer posting the advert, you'll see a 'Request Referral' button underneath the 'Apply Now' button. If you've scanned every business card you've ever received and then linked with those people on LinkedIn, there's a higher chance that you'll be able to request a referral.

Unlike Facebook, where your number of friends is seen as something of a status symbol, connecting with any and everyone on LinkedIn won't necessarily make you more successful. "It isn't about how many people you know, but actually who you know and what they know," explains LinkedIn's European PR Director Cristina Hoole. "It's more a question of quality than quantity."

Vetting your interests

LinkedIn enables you to summarise your hobbies and interests, just as you might do at the bottom of your CV. A few well-chosen disclosures can add instant merit to an otherwise static page; Bill Gates, for example, lists his interests as "reading, tennis and playing Bridge" whereas Barack Obama prefers "basketball, writing and spending time with my kids". What both Gates and Obama do share is that they – or their PR representatives – have undoubtedly agonised over these revelations.

A passion for Xbox wouldn't cut it, 'travelling' might suggest a lack of direction and 'driving my sports car' might suggest a lack of concern for the environment. While these men may have a lot more to lose, the basic principle is the same. It might be your greatest passion, but unless your hobby fits neatly between uninteresting and unethical, it's best not to mention it.

Your summary is your chance to sell yourself, so inject some personality into it. Blandly stating 'I am a London-based web designer specialising in database technologies. I am knowledgeable and friendly' isn't going to convince anyone. Compare this to 'I'm a forward-thinking web developer based in bustling central London. I'm highly knowledgeable and passionate about my field, with significant expertise in database technologies', and it's clear which is more likely to get you hired. Another good idea is to write like you talk. If you generally shorten 'there is' to 'there's', do so; it'll look far less wooden.

You'll find that your summary allows you to sell yourself publicly on a level that might previously have been uncomfortable. There's an unspoken acceptance that a LinkedIn summary can often come across as pompous – and within the confines of the site, that's OK. Boasts such as 'I was the only member of my team to achieve a perfect record' or 'I've been praised on numerous occasions for my strong leadership ability' may initially seem a little awkward to make publicly visible, but in LinkedIn they're not just acceptable – they're vital if you want to impress.

Public speaking

Networking is a big part of LinkedIn life, and you'll have opportunities to offer advice, discuss practices and advertise your services to other members. Asking and answering questions is a vital practice. It builds your credibility and gives others a reason to take a look at your profile – and hopefully be impressed while they're there.

It's worth making a point of asking and answering questions to establish yourself as an expert in your field and raise your social visibility. It also pays to write professional recommendations for your friends and colleagues due to the reciprocal nature of the act.

"Ask your contacts to focus on a specific skill or personality trait that drives their opinion of you," suggests Hoole. "Make meaningful comments when you recommend others, and mix it up; variety makes your recommendations feel authentic." A recommendation from an influential colleague is also likely to provide a substantial boost to your Google PageRank, and your audience is far more likely to believe a recommendation than your summary.

Showing the real you

While LinkedIn handles your corporate side, more socially oriented sites like Facebook play an invaluable role in portraying you as a human being. We all know what all work and no play does to Jack's image, and constantly being shown as unflinchingly professional may depict you as someone who's impossible to engage on a personal level.

An ongoing debate rages regarding adding your boss and work colleagues as friends on Facebook. The answer depends on how you use the site. Whether you're new to the website or have been using Facebook since its launch, it's never too late to craft your profile into a powerful outlet for both your business side and the real you.

Even if you're currently treading the thin line of acceptability, a little common sense combined with time spent getting to grips with Facebook's various privacy settings can quickly ensure that your colleagues only see what you want them to see. Facebook has recently undergone a major revamp, and users can now create 'friend lists' that control which users see which content. This is the key to using Facebook as both a candid diary of your personal life and a calculated portrayal of your interests outside of work.

Researchers at sociology site YouJustGetMe recently conducted a study into how we are perceived via social networking and whether this is the same as how we perceive ourselves. Their findings revealed that in general, people do 'get' each other. Rather more interesting, however, are the somewhat offbeat methods that YouJustGetMe recommend to ensure that people browsing your profile get to know the real you.

Posting a link to a funny video is, according to this research, the best way to get others to understand you as a person because the content of the clip reveals your sense of humour. Writing down what makes you glad to be alive or revealing the most embarrassing thing you've ever done also reveals a great deal about you. On the other hand, recommending an unpopular book or not using a real profile photo can negatively accept other users' perceptions of your personality.

Whether you're looking for a good job, eager for people to know the real you or even trying to find the perfect partner on dating sites, the same rules apply.

Playing it cool

Due to its humble student roots, Facebook still retains its 'LinkedIn for kids' image. This can play to your advantage, however; it's far more acceptable to be casual on Facebook than on LinkedIn. Compare Barack Obama's interests on LinkedIn with those on Facebook. "Spending time with my kids" becomes "loafing w/ kids"; the word 'loafing' does enough to suggest he filled out the form himself, and that for some sums up the President Elect's desire to appeal to the site's predominantly under-25 user base. He's far more revealing about his likes and interests, too, juxtaposing the Bible and JS Bach's cello suites with The Fugees and One Flew Over The Cuckoo's Nest.

Casual analysis of Obama's listed favourite music, books and films reveals a strong interest in the African- American plight, American history and Christianity, while musical tastes varying from the baroque high-culture of Bach to the political counter-culture of Bob Dylan round off his perceived personality.

There's little here that his opponents can pick apart, yet enough to earn the respect of Facebook's younger members without becoming farcical. If you have professional connections on Facebook, it's worth performing a similar analysis on your profile. The music you listen to and the films you like can reveal a great deal more than a carefully constructed personal statement, and manipulation is far less obvious.

Another good reason for listing your favourite film, book or artist is the chance that it offers to really engage with someone. Your love of David Lynch movies might mean little to many, but there's an outside chance that someone you regard as a valuable asset might be a fan too and use it to start a conversation.

Similarly, joining groups is great as long as they're relevant and acceptable. By acceptable, we suggest you devote serious thought before you join the 8,000-strong 'Vote British National Party' group, whereas joining 'Super carpenters of the world' is fine if you build things out of wood.

Getting personal

The best sort of profile is one you make yourself. A personal website is your most public-facing presence, and it requires no connecting or befriending to view.

There was a time not so long ago that owning a domain name based around your real name was seen as egotistical and unnecessary unless you were actively promoting your trade. Nowadays, it's a vital step in establishing your online identity. If your name isn't unique, try including your middle name, or looking for alternative top-level domains such as '.name' or '.me'. While it might not be as iconic as a '.com', it's how you promote that domain that counts.

A personal website will often be the first port of call for anyone searching for information about you. To give a good first impression, make sure that it features a clearly written summary of who you are and what you do. Other good ideas are to make it simple to navigate and text-based as opposed to Flash-based, as Flash offers little for search engines to latch on to.

The best use of your personal site is to clearly define yourself and what you do while providing a platform from which to access your other sites. This makes sure that anyone doing a little digging is able to follow your online paper trail accurately. How you use your personal site is down to what your aims in marketing yourself are. Do you simply want people to know who you are and what you're good at, or are you advertising a professional service? Do you want to make a name for yourself as a nice guy with an eclectic music taste or as a trustworthy and high-lying businessman?

The most common personal sites take the form of blogs. Keeping an online record of your life can be risky, but what will show you up far more than content is the frequency of your posts. Unlike a static portfolio-style site, a blog needs constant attention to keep its readers – and search engines – interested, and going for weeks without posting may give the impression that you find it hard to commit to things.

To make yourself stand out, the information that you provide needs to be unusual and unique. Simply posting links to interesting content elsewhere on the web will give your audience some impression of the sort of things you're interested in, but it will also starve them of your own voice.

While a personal site does need to be just that, try to take a step back and market yourself as a PR might. You'll find that unlike on social-networking sites, the majority of personal statements on personal websites are written in the third person. 'David is a leading developer' sounds less inflated and more authoritative than 'I am a leading developer'.

Try to avoid cliché; stating that you enjoy good food, relaxing with friends and walks on moonlit beaches won't get you anywhere. A bit more detail will create far more interest and increase the chance that your audience will connect with you on an emotional level. Stating a particular dish you like or the name of your favourite beach will do far more for how people perceive you. Similarly, negativity is a terrible thing. Resist the urge to list your pet hates; even if you're the happiest person in the world, you'll portray a very negative image of yourself.

Publishing platforms like Wordpress can also be augmented with social-networking plug-ins that display your information, and this can be useful if you want to incorporate more than simple links to other social networking sites. A Twitter plug-in will enable users to see what you're twittering without visiting the site itself, and Flickr slideshows can bring your snaps to a wider audience than your usual Flickr crowd. Even listing some of the Amazon book reviews that you've written will go some way to depicting who you really are.

Harnessing the net

Despite what a hundred social networking horror stories may have you believe, you've got to be exceptionally careless to allow any content posted online to affect your career or social prospects. The skill is in finding an online work-life balance and successfully deciding how much of either side you should reveal.

There's no right answer; the balance depends heavily on your social status, your line of work and the beliefs of your peers. Your boss may have absolutely no issues with you mixing Friday night with Monday morning – he might even feature in the photos. You might even choose to make your entire Facebook profile visible to the public in order to make full use of Google's crawling power.

What is concrete, however, is the necessity that you exist online in some form and that you protect the reputation that you already have – whether this means making sure that your boss can't view last night's drunken photos or filtering your stated interests to present a more rounded image of yourself. Employers may still ask for a traditional CV, but you can bet that the information gathering won't stop there.

The ultimate goal is to reach a stage where so much quantifiably positive information exists online that the paper CV becomes redundant. And with more and more HR departments accepting sites such as LinkedIn as valuable employment resources, it's a wholly tangible objective.

-------------------------------------------------------------------------------------------------------

First published in PC Plus, Issue 277

Now read Top 15 things you should never do on Facebook

Sign up for the free weekly TechRadar newsletter
Get tech news delivered straight to your inbox. Register for the free TechRadar newsletter and stay on top of the week's biggest stories and product releases. Sign up at http://www.techradar.com/register