The #1 rule for me is: Don't try to show too much.
It's easy to live with a chunk of code for a couple of weeks and think, "Damn, when I show 'em this they are gonna freak out!" Even during your private rehearsals you feel good about things. But once in front of an audience, the complexity of your code is multiplied by the square of the number of audience members. (It becomes exponentially harder to explain code for each audience member added!)
What seemed so simple and direct privately quickly turns into a giant bowl of spaghetti that under pressure even you don't understand. Don't try to show production code (well factored and well partitioned), make simple inline examples that convey your core message.
My rule #1 could be construed, by the cynical, as don't overestimate you audience. As an optimist, I see it as don't overestimate your ability to explain your code!
rp
