Backing up data is one of those things that so many people know they should do, but don't, either because they never get around to it, or think they'll be okay without it. If you're in the latter group, trust me, you'll realize you're not okay without a backup, probably when it's too late. If you're in the former group, take advantage the lighter workload that this time of year can bring and get going on your backups! Let me highlight the backup strategy I personally use.

First, please note that no single backup strategy is perfect for everyone. I approach my backups as a freelancer occasionally working from home, father, and Apple geek. The approach I use will almost certainly differ from what you use (or will use). This is just meant as a springboard from which we can remind each other about backing up our data.
 

Hardware

My main setup is a MacPro, which gives me the luxury of having up to four drives installed internally (more if you are clever), versus a laptop which is sparse on drive expansion. In my case, I have a 320GB system drive, 500GB clone (320GB for clone, plus a spare 180GB partition), 1TB media drive, and a 2TB Time Machine volume. But I could easily substitute an external for any of these if I were on a laptop.

Strategy

Regarding the backups themselves, I have a three-tiered approach to my backups:

1. Bootable system clone
2. Versioned local backup
3. Remote critical backup

Let's go through these one-by-one.

1. Bootable System Clone

This is a complete clone of my main system drive, made weekly using Carbon Copy Cloner (throw the guy a donation, too). This is a backup I rarely (if ever) use, but is invaluable. If I am working on a project, and something completely trashes my system (bad blocks, system drive failure, etc.), I can immediately boot off the clone without having to wait several hours to restore my system. I can continue working off this drive until I have time to repair the original system drive.

In all honesty, this isn't a necessity, but I have so many drives littering my office, it seemed like a no-brainer to have a bootable system clone.

2. Versioned Local Backup

I go the easy route here, and simply use Time Machine. Using a 2TB Western Digital Caviar Green drive, I can backup my entire system drive as well as my 1TB media drive, which stores larger renders, captured footage, my stock library, etc. I chose to use Time Machine because it's built in to the OS, and integrated into several applications I use daily (Mail, Address Book, etc…) There are several other options out there, but it just tends to work.

What's great about a versioned backup is the ability to recover files not just from a hardware failure, but accidental deletion or file corruption as well.

3. Remote Critical Backup

If something catastrophic were to happen to my home (fire, tornado, robbery), I want to be sure my most important files are safe. I don't just mean AE and FCP files for work; family photos, videos, tax, and insurance documents top that list above anything work related. So I make sure those go off-site. Luckily, software like Crashplan makes that incredibly easy.

For a very reasonable cost ($1.50/mo up to 10GB, $3/mo unlimited single computer, $6/mo unlimited up to 10 computers), I have unlimited off-site backup, including file versioning. There are other services like Mozy and Backblaze if Crashplan isn't you're thing. The important part is to get those files somewhere outside of your home. The nice thing about Crashplan, though, is you can use their software for free to backup to a friend's computer. All you have to do is give your friend a drive, have them install Crashplan, and enter a code on their computer. (And really, why not just reciprocate and offer to be a backup destination for them as well?)

I am slowly extending my off-site backups to not-quite-so-critical files, including those on my media drive. But it's a slow process. If I really wanted to, I could send a drive to Crashplan and avoid the online transfer entirely, but I don't find that necessary for these files.

Conclusion

In the end, you need to find a backup solution that works for you. If you only chose one, I really recommend going off-site, either with a service like Crashplan, Mozy, or Backblaze; or with a drive you store in a safe-deposit box once a month. The important thing is to get those files to another physical location in case something happens to your home. Beyond that, if you can use a local backup for easy recovery, add that to the strategy as well. The bootable system clone? That's just if you're can't afford any down-time for a drive failure.

Drives are getting cheaper and the best backup is one that you can afford to have fail.