Jeff gives the best advice of all – keep everything in standard locations.
There are some files I use in every project – company logo, time-code burn-in, digital juice media and music. While tempting to always import these from their permanent home on the internal drive, I always copy and paste the files into my project directory before importing.
I try to keep backups of the project file and all non-video assets on a 2nd backup drive – but also keep track of your tapes. If using P2 or SxS media, you should keep backups of your raw footage on hard drive. Drives are cheap enough.
For really important projects, I have begun keeping two copies on two drives from the start. A client will not accept “oh, the drive is corrupt, sorry for the week delay.”
Once a project is done, I use the Project Manager to create a smaller version of the project, and copy this to the backup drive. So a 10 minute project may have 2+hours of raw footage, but the final project at 10 minutes should only have 2gigs of video assets, give or take depending upon complexity of course. You could burn that to DVD for that matter.
When I move to my laptop with an external drive, sometimes the audio needs to re-conform, sometimes not.
Mike