Back Up Your Data on a Mac!!!!!!!!!

Nothing you do with a computer will ever be as important as making a solid backup.
Hard drives fail, it's a fact of life. When yours does, unless you have a backup, you'll find yourself facing expensive data recovery services or worse: lost data.
Ideally, your backup system should be redundant. In other words, create at least two backups on two forms of media. At the very least, you should have a clone of your hard drive handy should your primary system go south.