Okay, some people like to avoid it.  Some dwell in it.  In general though, their are rules to live by when it comes to debating.

1. Respect the fact that their opinion may not be the same as yours.  If you want respect for your opinions, giving respect to others will help them accept the fact that the two of you can just agree to disagree.
2. Their’s no reason to swear, or give any other kind of derogatory comments.  Attacking the person for anything other than the topic at hand is stupid.  “HAHA, your grammar sucks!” doesn’t fit into a debate about abortion, does it?  Instead go after their reasoning and pick it apart with your own facts.  Stay on topic, and do it in a polite way.
3. Their’s no need to beat a dead horse.  If the debate is at a stand still, the same arguements over and over again, it is time to move on.  Their are no new points to be made.  Agree to disagree and go on with life.

Those are the 3 general rules of debating, that I can think of.  If you have any more good ideas or tips, please feel free to share them with me!