First of all, find out what you are looking for in a university. Are you looking for top notch education, great financial aid, a party school, a competitive environment, etc.? After that, you should make a list of which schools you are interested in and rank the good things you are looking for and then apply to your top choices.
This will require a bit of research but with the internet, it's not that difficult to find the information you need about most universities. If you have already applied and now are deciding, then rank the ones you got accepted to and talk with your family or whoever is supporting you to go to university about your choices. Also it does help to go and visit the school to see if you like the feel of the campus.
Sometimes if the feeling is all wrong it can make your college experience into a nightmare so it would be helpful if you familiarize yourself with the university's environment.