try to post in moderation, people who post too much don't get respected (if you want examples, look for Igloos)
While I understand the reasoning behind this, it's not really fair to say.
Posting in moderation is good, but don't feel like you have to limit the amount of times you post.
What you have to do is ensure that you only post when relevant.
Don't go posting for the sake of posting. And if you do post a lot, then really try to be nice and follow the rules. If you post a lot, and are quite rude, or break rules, you'll get picked up on a lot quicker than if you posted moderately.
On that note, it's also pretty good etiquette on these forums to not post repeatedly in a topic in very short succession, particularly if no one else is really trying to communicate with you.
That rules is also pretty good if you ever partake in a forum game. Don't go making every other post. It's not very fun for others and it's a bit rude. And there's probably only so much to say about your avatar or your signature.
And another good posting rule is to avoid posting again and again in a topic, after yourself, before anyone else can post.
If you have something new to say in a topic, then

your post, rather than writing a new one.
There are exceptions however.
Bumping a topic is fine, even if the last post was your own.
That's posting in a topic that is atleast a day or so old and has moved to another page of the Forum you're in.
Don't do it repeatedly though if there's nothing new to discuss.
And posting twice to correct yourself is normally fine, in moderation, in the Drama and Help Boards, since you can't modify posts here.
You'll pick up what goes and what doesn't pretty easily here.
Follow the rules and you should be fine.
There are a couple of rules that are unwritten though.
That includes admitting to Trolling, as in, saying you purposely trolled people on a server.
Admitting to hacking or "phishing" other people.
Posting large graphic descriptions, especially if aimed as a threat at someone else (Like telling someone you'll kill them horrifically).
Other than that though, have fun.
Mingle in and look around.
Follow the rules and be happy.