Very impressive that someone is organized enough to start this planning so early - bravo!
In general you should look to distinguish yourself as someone who is a a scholar (tough courses, top grades, AP courses where available), athlete (varsity participation, organized HS level teams, captain position), leader in the classroom, leader on the athletic team and court/pitch/field/pool, leader in civic/ community change, leader in organizations/ student government, clubs. also be able to articulate how you lead, mentor, and innovate. There are specific activities that depending on the service academy or ROTC program application, specifically are called out in some cases- boys/ girls state, Eagle scout for all genders, gold star girl scout, national honor society, varsity letter, captain, JROTC, Civil Air Patrol, Special honors (all-state), etc.
For now, take the harder math courses that will allow you to take more advanced Calc and Physics in HS, even AP. for Navy-option NROTC or USNA mids, a foundation in this material is very helpful.
I will say overall make choices that allow you to put together an application that puts your best foot forward. Mock interview. get support on your essays. Stay out of trouble, make an impact in your community through the channels above.
If this is your dream, then best of luck to you. My son could have been described as a future military aviator at your age too - he earned his Eagle scout, is now a commercial pilot/ flight instructor, and he will serve as a Naval Aviator too now - sounds like you have a lot in common with him. He also got his pilot license when he was 16 - you can look into taking some lessons if you think this is your path. You can also get a class 1 flight physical to confirm if you at-present have any conditions which would exclude you from flying for the military (better to know sooner if so).
I would say take time to learn about all service academy and rotc opportunities and the mission of the Army, Navy, Air Force, Coast Guard, Merchant Marines, etc. Learn too about secondary roles - what will you do if you don't get the opportunity to be a naval aviator? What branch has the best backup roles for you? For many USNA and other service academies are a perfect fit, but described by others as a great place to be "from", not "at". for my DS he wanted ROTC, and has worked hard but also enjoyed a lot of cool beach parties, bonfires, pool/ volleyball parties, nights out at a country line dance bar with a gaggle of midshipmen buddies (hey, I don't judge) that would not have been possible with the rigors of USNA. Likewise the USNA mids are having experiences that are awesome that he isn't. Find your path. Good luck.