Second time giving this advice to someone today: make a to-do list.
I'm lead programmer, team captain, scouting captain, and Chairman's Award head.......yeah, we have a small team and I'm the only person who's competed before.
I suggest making a to-do list [or several] of everything you need to do, showing people the ropes, checking hardware, briefing sub-teams, making a schedule of all your matches, -oh dear, it's your first regional. Are you a rookie team or have other people on the team been to regionals before?
In that case, prepare to have fun

I went to my first regional in junior high and was hooked...
There are several threads around here that give great advice on regionals [
here's one].
I'd emphasize:
-Comfortable shoes, as a member of drive team you will walk MILES.
-Scouting can be very helpful long before eliminations: I try to brief the drive team on their opponents and alliance partners.
-Protein bars or something like that are nice, because if you're anything like me you'll never take a break to eat [although I recommend not eating much right before a match] Oh and stay hydrated, at Championships last year I remember a kid keeling over in the bushes because he hadn't drunk enough water.
-Try to have a quick team meeting at the end of every day, especially Friday, to talk about strategy and generally debrief
-Talk to other teams, especially the ones near you in the pit. The friendships you make at regionals are important.
-This year I want to have one of those little video cameras you wear on your hat....must record my last regional as a student!
-Batteries! Every year there are a few robots whose batteries fall out and drag pathetically on the ground while the drive team even more pathetically watches the match. Make a nice secure case for your battery if you haven't already. I've also heard of teams zip-tying their battery connectors together before each match and that sounds like a good idea to me.
-If you have a custom-made minibot deployment mechanism that grips the pole, or a Lexan tube-gripper, or any part like that that is going to be going outside the frame of the robot, make and bring a spare.
-Read the
team updates. The latest one has key points about communications, the router, and driver station versions.
-Hopefully you've already read
this CD thread, about lessons learned from Week 1 regionals. It's got everything from strategy to communication problems to scouting. Pay special attention to anything that talks about the FMS, communication, and the DAP/router/radio/wireless bridge.
Can't think of anything else...except do make to-do lists, lots of them. I find they both help clear one's brain in pre-regional stress, and make everything a lot more efficient at the event. GOOD LUCK
[Oh and have fun. A regional event is the most concentrated fun you will ever have in high school, in my opinion.]