Well, if you don't act n00b, you won't attract n00bs. Best thing to do would act as mature as possible, use good grammar and capitalization, think about what you're gonna say before you say it, and don't use shortenings of words like "Y", "Plz", "Ppl", and others like that.
Also don't be an elitist. Or, really, don't imply/say/think you're the best.