If you are using software that has large libraries – music software for example – store these on secondary or even tertiary internal hard drives if you have a tower system, or on FireWire or USB 2.0 external drives. This keeps them off the boot drive but still accessible. Internal hard drives are very cheap and come in huge capacities.
Also, if you are working with Photoshop or Final Cut, keep an eye on the scratch disk settings. This is where the app stores data temporarily as you work with it, but it doesn't always get deleted when you quit. Large scratch disk folders can be easily identified and deleted.
How to back up files to a DVD using either Finder or Toast
1. Finder supports native CD and DVD burning so you can perform basic burns without any additional software. In System Preferences > CDs & DVDs, make sure your Mac is set to open Finder when blank discs are inserted. Then when you insert a disc, simply drag files and folders onto it and choose File > Burn Disc.
2. If you have Toast (£70, www.roxio.co.uk) or Disco ($30 (£17), www.discoapp.com) you get more options. In System Preferences you can tell the Mac to open your desired burning app when you insert a disc. Choose a disc type – Mac & PC is generally the best – and drop items into the window. Click the Size column to sort the list by size.
3. In Toast's Recorder Setting menu you can access advanced parameters for your burner. This includes the write speed; if you're in a hurry, choose the fastest speed. If you've had reliability problems with discs not burning properly, choose a slower speed. You can also choose to write a session and continue burning on that disc later.