Level 10
One more think I thought of:  Shredding (and general file maintenance whether it's paper or electronic).

I have about a half a file cabinet drawer of "shred in 2018" in accordance with my document retention policy.  And I pull out files of former clients (fired, left, moved, died), date them for shredding in the future, and move them to the shred section of the file cabinet.  Then I only have to flip through current clients next year when I need to pull a file.  I don't have DMS software, just use Windows Explorer, so I do the same thing with electronic client files.  Former clients get moved into an Archive folder which saves a good bit of time during tax season not having to scroll so much to find the right client folder.

Other electronic files get scattered all over different computers so I make sure everything ends up in the right place.  I try once or twice a year to "clean the desktop".  It's a little more involved, in a perfect world I'd file everything in the right place as soon as I get it, but this isn't a perfect world and I'm far from a perfect person!  Random stuff ends up on the desktop or in Downloads and really should be filed somewhere else.  5 or so years ago (which probably means it's been more like 10) I borrowed a big whiteboard from a friend of mine and wrote a massive list of computer file types and then came up with a logical way to organize all of them.  Music, photos, personal finance, CPE, business records, client files, vacation info, just to name a few.  So now everything has a "place" and every "place" gets backed up.

Rick