1. create a drive image, that way all your content can be simply restored easily. Acronis is usually considered the best at this, but lately their quality seems to be slipping. I will also list some free alternatives
12. Use an Internal drive or external drive with eSATA. This is redundancy #1. This gives you quick access to your data instantly after an issue
3. Use an external drive (preferrably eSATA, Firewire if not eSATA, and if no other choice: USB 2.0 -- the reason is USB 2.0 is the slowest and eSATA is the fastest for data transfer) and keep it away from the case. Some people even go so far as to take it with them when the leave the house so if the house burns down they have the data still
24. Encrypt all data drives with a secure password using tools like http://www.truecrypt.org/ with a strong password
Notes:
1. Free alternatives include http://www.runtime.org/driveimage-xml.htm (requires Windows to be installed, so is limiting in some aspects), http://www.macrium.com/reflectfree.asp (faster than paragon, but isn't quite as robust. Better if it supports everything you need, though), http://www.paragon-software.com/home/db-express/features.html (limited incremental features, but can restore data from a created CD/DVD, meaning you can do it even if your Windows drive dies),
2. Some people say that for these type of things you should go with cloud storage, but cloud storage means trusting some random company to 1, keep your data safe, 2. not touch your data, and 3. not go out of business. Not many companies are so trustworthy as to meet those criteria for me. It is also slow since you have to upload and download the files, in comparison to local storage.