Several warnings, lol, mod humor...
Report and move on, do not respond to the offending poster, the mods tend to lump you in the same category as him when it's time to lay down the law.
This site appears intelligent and mature, but people on it tend to be pretty self-righteous and arrogant, just check out any politics or religion thread, you'll see what I mean.
Don't become a slavering Yahtzee cultist, just don't.
The mods here are strict, but pretty fair in most cases, so give them a thanks for all their hard work every so often.
Contribute to a discussion when you post in it, a lot of people here will report you for low-content posts (like just saying "I agree with him" on a debate thread, the mods actually want substance), mods take a dim view of it and I've seen more than a few probations handed out for it.
Do not make "USE THE SEARCH BAR!" your entire post, as the TF2 heavy says "Cry some more" at least contribute to the discussion if you're going to scold someone for posting a repeat thread.
Things people here need to just stop whining about and shut up: Halo, WoW, consoles, PCs, and whatever other crap people like to complain about on here.
If you must use memes, at least make them funny, we've all seen them several thousand times and we need something good to make us laugh at them.
A lot of people like or at least are fairly neutral towards anime, if you hate anime and think that anyone who watches it is an obnoxious 15 year-old who won't watch anything not featuring hot ninja chicks then go somewhere else where people care to listen to you.
No threads of the "Would Goku beat Superman in a fight" variety, to you more seasoned folks, these are called Vs. threads.
Be a mentor rather than a dick, if someone really is factually wrong about something, let them know, don't do it with opinions or you're just a self-righteous little prick.
Be prepared for a long debate if you post your opinion in a politics/religion thread, your views will almost certainly be challenged.
For goodness sake, don't disagree with the experts on something unless you actually are qualified to do so, some random guy disagreeing with people who've been studying something their entire lives (talking mainly science/history types of things here, religion is more subjective) will just get you laughed at here.
Don't start trouble between the Europeans and Americans on this forum, everyone comes out looking like an ass and some punishments get handed out.
Be a lurker for a week before you post, know what threads are dead horses, know what people here like and dislike, get a feeling for everything, and then post here.