Answer:
Prepare counterarguments for the presenter's ideas.
Think and organize your ideas before speaking.
Step-by-step explanation:
These are the two strategies that will allow you to carry out effective group discussions. In the first example, by preparing counterarguments for the presenter's ideas, you will be able to better address the concerns you might have with the speech, and the speaker would be more likely to address them effectively. Moreover, by thinking and organizing your ideas before speaking, you will be more likely to convey your ideas in a clear, concise and effective way.