To include some general rules and etiquette...
-Nobody cares if your roleplaying and writing skills are bad. There are people from all ages everywhere, and people understand when you don't totally get what is happening or if your character reacts in an unexpected way. Everybody started there, and everybody can help you get to the level where you're happy with each and every post you make. Just make sure you at least try to use proper spelling and grammar, it's very annoying to read a post written in 1337 or with terrible spelling.
-For those who are skilled roleplayers, if somebody is clearly at a lower skill level than you are and they ask for advice, don't just tear them apart and point out every single flaw. Say what they do well and how they can improve those things that they do not do well. If they don't ask for criticism, don't give it to them.
-There are no superpowers or appearing stronger than everybody else. No, you didn't just pin him before he could do anything, and no you didn't dodge every single hit he tried to land on you. You're just like everyone else in the fact that you can't do these things. Fighting is an interesting topic because everyone wants their own character to win, because many people show their personality through their character and if the character fails, it makes the person feel bad. Just avoid fighting as much as you can, and if you think someone has done something beyond what is normal in a fight that does arise, just ignore it.
-Arguing on the internet is like watching a pot until it boils. Nothing good is going to happen until you stop.
-Act your own rank. If a fight comes up, just stay out of it if it doesn't involve you.
Will add more once I think of more, and if an issue arises that isn't covered here. Any questions can be PMed to me.