Make at least three sets of backups. Keep one set in a different building from your office. The equally important corollary is save, save and save. I usually save a document with a new name at least after each draft. You can always throw out the drafts later.
Many people fear computer software or hardware malfunction.
But a worse case is a fire or theft that leaves you with no computer at all. Make sure your insurance covers all your computer equipment. Homeowner policies may require riders, but even then won't cover your laptop while traveling. A company called Safeware offers all-risk laptop coverage. Most new computers come with large-enough hard drives these days, but most still come with no more than half the RAM they need.