Studying in high school is nothing like studying in college. Don't think that you can just breeze through college classes like you do high school classes. Take all the algebra classes you can. Nearly all degrees require college algebra now. Do all the essays you can. English class will carry you all the way through college. Every class you take will require you to write essay papers. If you struggle now, in English or math, talk to your counselors and teachers. Tell them you want to go to college and that you need to really work on the art of writing an essay. Even if you hate math, learn the algebra. Do the word problems. They are practical applications for algebra and will help make the problems, make more sense. If you learn it now, it will be easier in college. You need to make sure that you have your financial aid in order BEFORE you register. Your life will go much smoother. If you run into a snag, don't give up, be persistant and patient. Talk to your advisors. They are lifeline to sanity.
I went to a school were nobody cared if you passed or not. It was really easy to slide by in school and hardly any teachers pushed you to do your best. I tried in school but not as nearly as hard as I should have. Now, I am paying for it. In classes I don't quite remember or know the little details I need to do certain things, so I spend so much extra time looking up and studying stuff I would have known if I would have tried harder in high school. If I could tell myself something now that I know now it would be to listen more, put away my cellphone (it can wait), review, study harder, and to of applied for much more scholarships because college is expensive.