1) It's not a race. I've seen so many dicks on the track that think they're the next Valentino Rossi and all they do is F it up for everyone else when they inevitably crash or cause a crash.
2) Don't outpace yourself. As you're probably aware, the bike will give little warning when it's on the edge of control and if you're new to track riding, you'll probably miss the warning; i.e., one second you'll think you're fine and the next you'll be on the ground.
3) Make sure you're bike is properly prepped beforehand; e.g., safety wire where necessary, new-ish tires, tire pressure gauge and air compressor if you have one, etc.
4) Since it's your first track day, you'll probably be required to ride behind an instructor, at least at first. Pay attention, he or she can probably show you a thing or two.
5) have fun