This was going to be my first question.
If you're brand new to tracking - I usually suggest getting rid of the tune and have a go with a stock engine. The LAST thing you want to add to a car before going onto the track is power.
For tracking in order of importance:
1. Brakes - you can have 5000HP and if you can't stop, you crash. Stock brake pads may be okay as some have pointed out. Going to a more endurance type of track pad will help with brake fade and last longer without chewing up your rotors. Fluid I would change no matter what. It's always good to have a high-temp fluid to avoid boiling over or a soft, spongy brake pedal.
2. Seat time
3. Seat time
4. Seat time
5. Seat time
6. Handling - This would include making changes to springs, shocks, bushings, alignment, tires etc.
7. Seat time
8. Seat time
9. Seat time
10. Maybe adding HP. Adding HP includes adding heat. Heat is the enemy for tracking and can cause more problems. Yes, and intercooler will help with the intake temp, but what about oil temps (do you need to run an oil cooler and diff cooler?).
I drove my street car on the track for eight years. I did everything on the list above except for adding HP (I had a tune on a NA BMW330i, that increased the power from 255 to a whopping 270 maybe). Now I race in SCCA and AER endurance races.
As you can see, I'm a big fan of seat time. It's the biggest difference that can be made out on the track. I was quicker than a lot of my friends that had either M3's or highly modified 335's.
TBH: I wouldn't mess with brakes at all. If you're going to track your car, it's the last thing you want to worry about. Going for a brake pedal that isn't firm or having a longer and longer travel will ruin your weekend.
I'm assuming you're not going to remove the APR Stage 2 tune, so you're actually playing with more HP than the car I race.
Be careful. Be smooth. Don't scare your instructor.