Point out inconsistencies and one-sidedness in your opponent’s argument. This can be particularly devastating because it destroys the credibility of your opponent. You could also turn your opponent’s accusations against him. If he accuses your side of anything, demonstrate how his side is no better in that respect.
Don’t claim perfection. People who claim to be completely and totally correct can lose because this makes their argument seem unrealistic. Admit cases where your argument might have some weakness, but then point out how this weakness is minor, and then point out a weakness in your opponent’s argument.
You need ammunition in the form of resources that back you up. Whenever they try to call your argument completely wrong and incorrect, just bring up another credible source that says the same thing that you are saying. Instead of the opponent calling you wrong, he is now calling all of your sources wrong. This tactic is very helpful when you are very confident in the correctness of your argument and have a lot of sources. Make sure that you do a lot of research before the debate.
Know your opponent’s reasoning. If you know the logic that he is using to come up with his argument, you can directly attack his argument at its foundation. You can point out where he is wrong and convince him by explaining your logic. Just arguing your point over and over again cannot win against a person who believes in the correctness of his logic, since you aren’t actually pointing out where his logic is wrong. If you can get him to see where your logic may be more reasonable than his, he will back off his claims.
Believe in your argument. Even if you wouldn’t normally believe in your argument, you have to put that aside in your mind. Those who are able to truly trick themselves into believing in their argument are often the ones who win. A confident person will defend better and be able to find loopholes in the other person’s argument. There is not much to explain, but this is possibly one of the most important things on this list.
Don’t go into defensive mode. When the other person’s attacks are strong, don’t start saying things such as “yeah, well, your side is…” This is basically admitting your defeat. Another thing to avoid is simply saying things along the lines of “no it’s not” without any claims or evidence to back you up. This really does nothing to stop or disprove the opponent’s attacks on your position. It also allows the argument to center around the flaws of your side, which is never a good thing.
Go on the offense. Say things along the lines of “This is wrong with your argument, and here is why”. The most important part is the “why” because it turns your attack into something that is much more credible and powerful. Now, instead of simply saying that you are wrong in order to dispel the attack, your opponent must prove that your “why” is wrong. This focuses the argument on what is wrong with your opponent’s point of view. Make sure that your opponent always brings up credible facts for his defense. Try and make him go into the defensive mode described above, which causes him to basically admit defeat. Whatever you do, always have a reasoning behind your attack. Not having one reduces your credibility and makes it easier for the opponent to shift the argument back over to you.
Don’t make claims you can’t back up. The moment your opponent is able to prove something about your argument is downright wrong, the debate is much, much harder because you are already known to have been incorrect. This causes people to question every other claim that you have made, which makes all of your offense and defense much harder. Make sure that you point out whenever your opponent does this, as it will help you a lot. Being able to back up your claims and point out where your opponent can’t is another reason that you should do research before the debate.