1. NEVER use the stall directly next to an occupied stall if others are available.
Doing your business in public is creepy enough. Doing it with a stranger 2 feet away from you is worse.
2. Do not leave your pubic hair on the seat.
At least blow it on the floor...If you have so many that you are actually shedding, you should maybe look into buying some hair clippers.
Nobody wants to see your poo (unless we have the same plumber.)
4. Do not permit your children to peek under stalls to see if they are empty.
This happened to me today. Good thing I had trimmed my pubes. But that said, I do not want to be your child's first anatomy lesson.
5. At least pretend to wash your hands.