A boring backup routine that works
Three copies of everything that matters, on two kinds of media, with one of them somewhere else. That is the entire plan.
The routine
A nightly job copies documents to the second machine. Once a month a reminder tells me to plug in the external drive and sync it. Twice a year I try restoring a random folder, because a backup you have never restored is only a hope.
rsync -a --delete ~/Documents/ backup-host:/srv/backup/documents/