[header] How to rebut better [title] Know your argument. [step] You need to have a solid grasp of the topic, your stance on the topic, the reasons that support that stance, and the evidence that you will use to support those reasons. It's easiest to know your argument if you have a written case, but in an impromptu setting, you can keep up with the argument you or your team is presenting by taking good notes. 
[substeps] If you have a written case, study both the case and outline before the debate. Underline important points, and know where your evidence is sourced.