There are also "cloud" services like iBackup, which for a fee will do automatic backups of your data. Failing that, Google Drive or Dropbox can be used to sync your data to the cloud (especially nice if you have more than one computer or an iOS device). Cloud storage has the added advantage of being out of danger of being lost if your house burns down. DVD backups are nice, but they'll melt if you forgot to turn off the gas.
Also, make sure you have good installers for your various applications, just in case.