You can exchange small notes, have a word after the speech, strategize during another person’s speech, draft points to cover better or dismiss. As long as you are focused on the debate, you are expected to work synergically to make the debate interesting and lively.
Just because there was a hiccup in your speech doesn’t mean your whole speech was bad or your team has lost. Debaters work as a team during the competition, if the point made is pivotal, let your next speaker know with a short note.
Keep yourself hungry with curiosity. Everyone loves a teammate that remembers specific and unusual information on a topic. Reading about different topics during the year will help you to broaden your research bank but if you can read more about one you are passionate about. Not all topics can be covered in detail. You might also arrange to divide up hot topics to be more prepared with updated information.