OK, I'm not sure about how you do it in the US as I'm from the UK, but I'd suggest looking at university's websites and look at the entrance requirements to study medicine. It should include the qualification subject you need to do in order to study medicine. Then I think it's just a case of doing that subject at college and getting a great grade, and then applying for medicine.
I'm unsure of how the US education system works - is it that you get a degree at college say in a science subject that's related to medicine and then you do a few years training as a doctor? I think I've got this entirely from TV. I'd be grateful if someone could clear this up - I think it's the main gist of things though. Ignore me completely if it's wrong!!
Choose your college on the location, its reputation, whether it does the course you want to do, whether you want to spend a few years of your life studying, whether you feel at home there etc.