1. Don't overlap wheels.
If you need to move to one side or the other to find the draft, fine. But never overlap wheels.
2. Don't be afraid to talk.
If he's going to fast for you, say so. Don't try to close the gap, because when he pulls off, you'll be gassed.
If you want to take longer pulls, say so. Don't leave him to assume anything.
If your rider is pulling off on the wrong side (leeward side), say so.
If you want to lighten the mood, do so. An occasional joke helps numb the pain, and shows that you're on top of things.
3. When you pull off, give him enough room to get past you.
I hate it when they pull off and make you thread the needle between them and the shoulder. How unware can a rider be?
4. Never cook yourself on the front.
Don't be a hero. Just do your part to maintain the pace.
5. Find the draft and stick to it.
If you're on the back and you're wasting energy, you'll pay sooner than later.
6. Pay attention.
Late in the race, when you start to fade, that's when accidents happen.
7. Smile. Have fun. It's better than yard work!