Repositories are awesome, and we should have more of them.
I recently completed BJ Fogg's Tiny Habits, and it's a pretty lightweight way to install new habits (recommended). However, I realized I could use a better repository of useful habits.
So, please use this thread to suggest habits that you've found useful. Bonus points for evidence/anecdata of usefulness.
Obviously, 1 habit per comment makes upvotes a clearer signal of collective approval.
Keep a checklist of maintenance items to do before work/school, including things you should bring with you. Print this out and tape to a wall, using font large enough that you can read it from some distance away.
A friend has a piece of paper with "Ensure pants are on" taped to the inside of his door. I don't think he has ever left the house without having pants on.