It's all been said above, but just to reiterate:
- Pack your stuff the night before along with print outs of your list
- Drink lots of water on the day (I usually limit myself to one [admittedly strong] coffee around lunchtime)
- Talk to your opponents about their lists and during the game - both to have a laugh and to clarify things before they become an issue
-
Take pics and write it up
(it's hard to remember to take pics though while a game is going on!)