I keep a special file folder for ongoing work, trying always to put in what’s latest. That way when a client refers to something like that last PowerPoint or the white paper I did for them I can find it right away, even if they reference it by some other name.
I file using job numbers and I invoice that way too. I don’t expect my clients to name things the same way I do though. So by keeping up with my filing of what’s latest, it helps me keep from spending more time trying to track something down than actually working on it. (Which used to happen more often than I care to admit!) But it can take time to file and when I’m busy it’s not a priority. However, I can do it in short spurts between other things to keep it from being too tedious. Then when the effort pays off with time savings later it reinforces the motivation to keep on top of it. Well, I’ve got to get back to filing now!