The Selectivity Factor
You don't have to be the best student in the world to go to college. You do need to be a competitor. Most students think that "selective" colleges are academically elite colleges. That's not always true.
Selectivity is more a matter of supply and demand. The more students there are competing for a given amount of seats, the more selective the school will be in filling them. Why? The school has more choices.
Every college determines what it's looking for, but the best thing you can do to increase your chances of getting in is to apply to schools for which you're well-suited in terms of academics, test scores, and other credentials.