don't focus on being fast, just focus on being smooth.
be cognizant of your brakes, especially based on prep and feel.
don't just barrel with speed down the straight into the corner and fuck it up as a result, focus on being prepared and taking the corner properly, it will be trivial to add speed going straight later up until corner entry.
put on some sunscreen.
drive your own line - especially as a newbie you will fixate on a car in front of you. you may be catching them but that may just mean you are less sloppy than them but still not doing something clean; once you do catch up to them, you may find yourself staring at their ass and starting to poorly drive your own line, they will feel pressure (especially if you sit on them and they are not pointing you by) making them more likely to screw up.. and you may very well target fixate and follow them right into the same mistake (off the course or into their ass) - don't do that.
also if someone catches you, it's a closed course, they are faster. if you have 500 hp and some 110hp miata caught you, point them by and ease off the throttle so that they can actually pass you on a straight.
check tire wear marks and pressure, although really for your first day that doesn't really matter, just try to learn where you should be on the course and work on smoothly taking the turns. you probably won't be braking close to properly until you get a ride along and see how an instructor is doing it first either, definitely take advantage of going for a ride along in some instructor cars to learn that and the race line.
also report back on your experience!