A lot of people are under the impression that the college admissions process is shrouded in mystery, that colleges are looking for specific qualifications or qualities without coming out and saying so.
But a quick trip to a college's website will show you just how open colleges are about what they want from applicants. All the required tests, the recommended academic preparation, and the elements required to consider your application complete will all be spelled out there. Believe me, if they want it from applicants, they won't hide it.
The perceived mystery comes when people ask questions like, "What activities do you prefer?" "What are your SAT score cut-offs?" "What are the best topics for essays, the minimum numbers of community service hours, and the best summer programs to do?"
You won't find answers to those questions because there aren't any. Yes, the Naval Academy will probably expect different activities than Julliard will. But beyond what they describe on the websites, most colleges don't have set policies about what they're looking for. They want smart, engaged students who will make interesting contributions in and out of the classrooms, and there are lots of ways to measure that. They don't want one type of student. They want lots of different types.
So worry only about the basics. If a college mentions that they want you to do something, give it to them. But beyond that, don't worry so much about what's going to impress them. You could spend four years trying to guess which activities Harvard or Rice or Amherst wants you to do and nothing will be as impressive as if you'd just done what you wanted to do, excelled, and enjoyed yourself.
That's why the most successful colleges applicants worry only about the basics of what colleges want, the stuff that colleges come out and ask for. Beyond that, those applicants don't obsess about whether they're doing the "right things."
The right colleges will appreciate what you do as long as you get the basics right.