Thanks to Reddit, people have compiled their DO'S and DON'T in public bathrooms. Some of these should be common sense, but, well you know.
1. Don't look through the crack into a stall.
2. Don't talk to strangers about ANY subject.
3. In a men's room, pick the urinal furthest away from someone else.
4. No grunting.
5. In a women's room, if you're at the sink and someone's in a stall and not peeing, hurry up and leave. She clearly wants to poop but is waiting until you leave.
6. No laughing at loud noises coming from the stalls.
7. Wipe the seat if you splashed on it.
8. Flush. And then flush a second time if you have to.
Here's a funny video done a while back making fun of "in office" bathroom behavior.