Do things that make you happy. Figure out what you’re interested in and try and find a way to pursue it. It’s not worth it wasting hundreds of hours on something you think colleges will like (especially since that generally generates a laundry-list of ECs, which won’t really stand out to colleges). If it ends up helping you get into XYZ College, great! If not, at least you spent your high school years meaningfully.
Treat everything as a learning experience. It might be hard to stomach your first rejection or bad grade, but don’t let it get you down. Use it as motivation to do better next time! On a related note, don’t be scared of failure. Try out for things that you are interested. The worst that can happen is that you don’t get in. I’ve applied to many MANY positions/programs…was accepted to some, and was rejected by even more.
Remember the important things in life. You might get caught up in the stresses of school, but never neglect your health or your family/support network. Appreciate all the people who love you, because they won’t always be there. Take care of your health; you only have one body.
And finally, don’t procrastinate. Easier said than done 