As for data, I would recommend to seperate files in to:
- Important documents (encrypt it)
- Memories (pictures and such)
- Others, not so important/replaceble (movies, music, etc.)
This allows you to decide which data to copy to which storage solution, if you have multiple storage devices. Having multiple storage devices at differnt locations is pretty handy if a location is effected by something (fire, flooding, etc).
I use a mixture of 2,5 HDD's, USB flashdrives and stored hidden in devices.
I do a backup of the user directory (Drive letter:\\users\username) except for the download folder. Any downloaded installation programs get copied onto a DVD-R. It's enough to reconstruct things in case of a drive crash. The user directory includes desktop, pictures, movies, music, my docs, contacts, favorites, etc.
Important or sensative documents are already encryted as a countermeasure in case I get hacked. Think of it as a cyber home safe. Like most people here, I prefer to make the odds in my favor.