My biggest tip would be relax and have fun, if you are nervous it will make things worse. Take your time and remember the pedals are not binary switches.
I never bother to adjust the car in any way other than swapping from slicks to something with a little more tread. My view is you learn far more driving it than tinkering in the pits when you are there to have fun not find every last hundredth of a second. Also the grip may not be where you expect it so experiment with your lines. The only word of caution would be standing water, thin bands are usually ok wider bands can be interesting.
Oh a motorbike waterproof gimp suit helps with staying dry.
Hope you have a good time.