Exciting! I'm sure you've seen the great list on the "agility for dummies" thread.
I just got back from my first trial last night, and I can tell you, I panicked more than was needed
. Everything went very smoothly. The best item I had with me was a container of squirt cheese - perfect for keeping Meg focused on me as we walked through crowds of dogs. She was like a baby sucking on a bottle
.
I don't think I can offer any better advice than I got on that thread. Just relax and have fun!