A few thoughts....
Enjoy High School, you can be both a competitive candidate and enjoy high school
Explore your passions, leadership is great, but it is incredibly easy to see through some of the positions people have, choose positions you genuinely care about.
Sports, most USAFA cadets have played at the varsity level in high school and there is extreme value in dedicating yourself to something, but find something you enjoy.
My personal opinion is having a job is great, I personally wouldn't worry about what kind or responsibility level, but working also teaches you things, and there are a lot of skills you will learn.
Feel free to send me a dm if you want more specific info.