I love to debate. No way around it, I love to argue with people on topics your parents tell you not to argue about (i.e. politics, religeon, and society are three of my favorites) but I have to say there is certain etiquette into a good debate.
One of these things is to back up what you're saying. You need to know your sh*t so you don't sound like one nonstop ramble. Know what you're talking about before you open your mouth. And when you're losing, I understand the urge to fight to the death, but just bow out gracefully. If you're proven wrong, either admit it or stop.
Secondly, don't just pointlessly yell/scream/get louder. That's when debating turns into just an argument.
Thirdly, be a good sport. Everyone has their opinions they're entitled to, so just learn to respect them. Not everyone's for/against abortion, not everyone's for/against gay rights, etc. Just learn to accept their beliefs and don't be so narrow-minded.