I had a bunch of 9/11 truth debates recently, and there is one tactic I find to be useful that I wanted to share. It is simply trying to structure your debate so that your opponent has to prove a point. For instance, if the debate is all about you having to prove that 9/11 was an inside job, then they can just ignore you, or choose not to believe facts. If the debate is about them trying to prove something -- for instance, that bin laden did 9/11 -- then you can use your knowledge to shoot them down, and to prove that they are just a dumb sheeple who doesn't know anything and who needs to wake up ASAP.