For debates/Congress/Extemp/etc.:

Structure/organization is critical. Therefore, provide a roadmap: state your thesis, state your contention(s), and provide a brief summary up front. Before transitioning from one contention to the next, summarize what you have just demonstrated (e.g., a statement that starts with "Therefore..." and then basically restates the take-home-message of that contention.

Arguments must be sound and should be easy to follow. Don't make assumptions.

Delivery: I care far more about quality than quantity. One of the strongest PF arguments I judged had only one contention. Speaking loud and fast is not persuasive; making a good argument is.

Rebuttals, etc.: Use cross examination time to undermine and/or demonstrate the flaws in your opponent's position. Be specific and direct.

For POI:

Great character development with clear distinctions (blocking, posture, voice, etc.) is vital.