Here are a couple of things you can do:
Set up your schedule to keep your options open. You don’t want to get to senior year and find you haven’t taken prerequisites for classes you want.
This also means staying broad at the beginning.
Be open to new opportunities snd experiences. It’s amazing how often people find a passion without really looking.
Be open to new people. You are all on an exciting journey together and were granted admission because you each bring someone to the community. Enjoy this and learn from it.
Connect with your teachers. Private schools tend to make this easy.
Keep a bullet journal-- noting why you chose the courses and activities you did and then checking in on how the expectation matched the reality, what you like, what you don’t, etc. This will help you make better decisions for yourself going forward and may even end up including some inspiring for college essays. You won’t be able to do everything - this will serve as a reminder of what is genuinely exciting you.
Last, be present. These are 4 really important years of your life, not an extended admissions test for college. It sounds like you’ll be spending them in a rich environment-- immerse yourself in it for what it is.