Funnily enough I never got banned in almost 4 years of BBSing until a month or so ago when I posted in a slightly spammish thread and got destroy banned. So I guess most people will get banned at some point, even if they are experience and well-knowledged in the rules. Everyone makes mistakes.
As for starting out however...it is best to be a bit more cautious with your posts and read the rules thoroughly and browse topics before posting in them.
You'll have a few slip ups at the start, I had my slip ups when rules were a bit more leniant so got away with a lot more. Just learn from them really.