1. No Godmodding. Earth Ponies don't have amazing strength. Pegasi can't blow ponies back with the flap of their wings, and Unicorns aren't good at every single kind of magic, they usually only are good at one kind.
2. Roleplay in the third person. (Ex. of what not to do: I glanced at the pony next to me, before snorting and quickly taking off into the air with a flap of my wings. Ex of what to do: Burning Ash glanced at the pony next to her, before snorting and quickly taking off into the air with a flap of her wings.)
3. Topics going at the same time doesn't coexist. If your pony is in the middle of one topic and you join the different one, your pony doesn't know what happened in the one you were in the middle off. A.k.a, no paradoxes; the reapers will get us if you do that.
4. Don't post in old topics. If they are over a month old, they are dead. You hear me? DEAD!
5. Give members a chance to post. Don't leave people out of topics just because they have a busy life and can't get on every other hour. That is just silly if you can't wait that long.
6. No randomly turning into an Allicorn cause you are bored; only Twilight Sparkle can do that.
7. No controlling other people's ponies. No, not even with mind control.
8. Be realistic. Yes, I am telling you that in a world with colorful ponies. If you are a filly fighting a Usra Major, you can't beat it up with a single punch to it's nose. That just ticks the big thing off.
9. Try to write with good grammar and spelling. Please, some of us just can't handle the noob talk.
10. Go with the flow of the topic. If somebody important is visiting Ponyville, don't go and make the topic all about your day at the spa. Sure, Lotus and Aloe might love it, but the important pony that is visiting won't.
More will be added as I come up with them.