There's one thing that every email you originate should contain, and that's your email signature. Think of your signature as your final chance to grab someone's attention, but be aware that there's both good and bad attention.
A sloppy email signature or one that actively annoys will leave a bad last impression on anyone reading your email, whether it's the original recipient or anyone your email ends up being forwarded to.
Where to start
So how do you stand out? Firstly, while it's fine to inject a little personality into your email signoff, it's a very fine line before you topple straight over into either being too informal or downright casual. The standard "regards" may be a little stiff, but it's also safe for just about any email you might send.
Next consider what information about yourself you want to convey. Your full name is a given, as is any company or business name if it's a work email you're sending from. It's also fine to include methods of communication, but here less is arguably more.
If you list your email, phone, Twitter, Facebook, LinkedIn, Instagram and physical address, you're quickly overloading the recipient with information they may not care about, as well as bulking your email signature out by multiple lines. If you've carefully crafted a short and succinct email, do you want it ignored because your ten-line signature makes it seem like it's a lot of work to read?
Ideally, your signature should include your full or business name, your email address and a contact phone number at the minimum. There's some argument that says that email addresses are a little redundant if you're sending out an email in the first place, but the reality here is that the signature gives you another contact point for ongoing communication.
If you're after some kind of response from your email, it makes good sense to appear as approachable as feasible. Equally, many email clients can scrape this kind of information from emails seamlessly to build up contact lists.
You've also got to be aware of mobile clients and data limitations, and that means that image-based signatures should be used sparingly, if at all. An image signature does give you complete control over the appearance of your signature, but some clients will strip out images on first load, especially on mobile clients.
If you absolutely must have an image signature, make sure you've got ALT text to convey the same information to cover all bases. Signatures should also ideally be kept under 80 characters in length per line, again because you can't control the screen size or layout of the recipient's email application.