Too many people today don't backup their files. And of those that do, many don't do it well. An easy way to remember a "safe" way to backup your data is with the "3-2-1 Backup Rule" which goes like this:

• Keep 3 copies of any important files (your primary/working copy counts as one)
• Store your files on 2 different media types (Example: Hard drive and in the Cloud)
• Always have 1 copy off site

With the 3-2-1 rule you can be relatively confident that you'll always be able to access your critical data, even after a catastrophic failure.

Another rule I live by when it comes to backup is:

The only good backup is an automatic backup.

If you're backups aren't automated, there's a good chance you'll forget to run them or (in my case) just be lazy about it and think, "I'll back it up tomorrow." at which point a failure occurs and you're shit out of luck.

For those of you without a backup plan in place, I'd like to recommend a service I use, CrashPlan. CrashPlan allows you to backup to any of your own computers that also have CrashPlan installed for free. You can also backup to local folders and external drives and (with a little hacking) network drives as well. For a (reasonable) price, CrashPlan also supports limited and unlimited online backup plans. Clients are available for Windows, Linux and Mac operating systems, so it should work for any system you currently own.