My first autocross experience was pretty eye-opening when it comes to driving fast in other-than-a-straight-line. You will very likely get addicted to this, fair warning. There are more costly vices out there, though, right?
Try to get good rest the night before. It can really make a difference in your concentration.
Make sure your tires aren't underinflated.
Do the pedal dance before you go out on the course. The stability nannies will throw off what you're feeling with the car if they step in during your run.
You're very likely to, like I did, walk the course a few times in the morning and think "Ok, I think I've got it, not too bad" and then once you're out there and take your first turn, you look up again and all you can see is a sea of cones with no idea what to do next. That happened on my first run, and the only reason I got through was because I had an instructor sitting next to me guiding me through. After that I got some more confidence and sped up through the day, but it started to rain after lunch, and on my first run out in the rain I had another moment halfway through the course where I took a turn and had no idea where to go all over again and missed a gate. No instructor with me that time.
It's easy to want to get right to going out by yourself and running solo, but even after doing this for about 5 years now I still take one of the instructors with me on my first run if I can, and focus more on getting the course right than being fast out of the gate. If you blow your first run, it's very likely to make the rest of the day tougher until you get a good, clean run in. Better to get it in early and have a good baseline to work off of.
Even when you start to feel more comfortable out there, don't feel bad about taking an instructor with you to start your day or if you keep having trouble with the course. It's especially good when you find an instructor that you gel with (and/or who drives a similar vehicle) because the more comfortable you are out there, the less unnecessary thinking you'll find yourself doing. To me that's probably the easiest and best thing you can do for yourself is take instructors with you as often as you can, and gradually build up your momentum through the day as you gain confidence in yourself and what the car can do before it reaches its limits.
At the very least, having another person with you puts some weight on the right side of the car, which will help balance the car out better on right turns.
Keep looking up and looking ahead, and not just through the windshield. You've got three pieces of glass to see through, so don't be afraid to use your neck muscles and turn to see as much as you can before you drive up to it.
If you hit a cone, you hit it. Forget about it and keep focused on what's next. Thinking about that cone is just going to snowball into more mistakes ahead since you're not thinking about what's ahead of you. Think about it after you finish the run.
Don't expect to blow the doors off the car on the first run or even the first day. Have fun, and enjoy learning just how much you can really do with this car. This is the kind of thing the car was built for.
