The rules here are very simple, because we are all very easygoing. <3
Play and be active. If you are in a feature position and take a character and then never ever post, I will find a new player for that slot no matter how great your app is, though it will break my heart to do so! Also, you are expected to reply to any tag within a week at the absolute latest, hopefully as soon as possible. Otherwise I will be sad. And who wants me to be sad? :(
Write what needs writing. Make sure your post contains enough information to engender a reply -- there is no minimum or maximum length. Just have fun with it and the words will come. Don't stress. The hallmark of an "advanced" writer is being able to turn a finished thread into a single story, with well thought-out multi-dimensional characters. If you have fun, the writing will be awesome. I believe in you.
Don't be a jerk. It's silly to assume that everyone will be friends, because people are people and sometimes people clash. That's totally cool. But please do your best to coexist peacefully, do not Rile Up The Peanut Gallery, and if you have any problems with anything at all, see Cal to fix it.