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.
Assuming this is for one-night stands... Carry only one and if your prospective partner(s) cannot match your contribution, forego the activity: they are probably not as careful about safe sex as you want them to be.
I really wish this were good advice, but IME the correlation is not very strong.