For the love of God, use version control and then back it up, offsite. It doesn’t have to be a fully fledged Git install. As long as it doesn’t involve you repeatedly using ‘Save As…’ with an ever-extending filename suffix (‘-version-15-nice-edit.doc’) it’s fine. Unless you are writing code. Then you really should be using a code-oriented version control system. Like, Git. Too many people have lost too much work for this to be anything but an utter and total requirement.
There’s another ground rule, but it’s not one that can be summarised in a pithy little paragraph. A sentence though, is possible:
The Medium Matters.
Hang on. Bear with me. I’m going to make this a proper big-arse heading. All fancy-like. A big thing needs to look like a big thing.