Here are my top ten debating tips...
1. Prepare well. Know what you are going to say, what your team members are going to say and have some idea of what the other team is going to say; before the debate starts. Get to know the other people in your debating team (e.g. find out whether or not they like having help with rebuttal) and praise them when they have finished talking.
2. Use logic to develop your case and make your points.
3. Don't get drawn into personal attacks or look at the opposing team when rebutting.
4. Stick to the subject being debated and don't say anything that will not strengthen your case.
5. Have passion when you speak even if you don't like or believe what you are saying.
6. Don't waste time introducing the third speaker; everyone knows what they are going to do!
7. Have a very strong (1-2 sentences) conclusion. People remember most what they hear last so really drive your case home.
8. Don't be afraid to make a fool of the other team (as nicely as you can), if they make a mistake. Try to use humour; it seems to work the best.
9. Appear like you are enjoying yourself, even if you are not because you are stressed out to the max like you SHOULD BE when debating.
10. Be a good winner/loser after the debate and shake the hands of everyone in the opposing team.