1. Don't forget to fill up with petrol beforehand- you might get a few more mins before you run out of fuel

2. Petrol can is a good idea- but make sure you have somewhere/someone to leave it (and other stuff). Don't leave it crashing about in your car!
3. You don't have to hammer it every lap- get your eye in first, the once confident alternate between a couple of laps going for it (fun!) and a couple of laps a bit slower trying to get everything perfect (lines etc)
4. Do a cooling down run before coming in- cool engine and brakes.
5. (maybe too late) brand new tyres aren't ideal, the tread depth means they heat up more. Hope for rain

Fronts will get massive wear. Could put older ones on front newer on back if you haven't already. And expect to probably replace the old fronts after the track day unless they have quite a bit of tread to begin with.
6. Take regular breaks, speak to and watch what other people do, easier to learn from others' mistakes when you aren't hurtling around
7. Don't push it at the end of the day- if you're tired then stop. "one last lap" can be dangerously appealing! Oh, and prime yourself to drive home slowly- it'll feel like slow mo after a track day