Help prepare for a debate?

We're doing presidential debates in history cl, and we are each igned a president and to have a mock trial proving who was the superior leader. I have Kennedy, and my first debate is against (I know it must seem easy...) Nixon, yet I am bad at debating and my opponent is a proficient persuader. I know to bring up the Watergate scandal, yet I don't know how to counter the Bay of Pigs fiasco if he brings it up, and it seems like Watergate might be my only ammunition, and I might lose because of that. So, could anyone help me to prepare for this debate? (If i lose to Nixon, that's gonna be embaring...)