If you want to play Division I, you need to be good. Like, really, really good. Ideally, you'll have been a starter for four years, all-league/district for three, all-state for two, all-American for one, and your club will regularly compete in national tournaments (source).

If you're okay with playing Tier II at a D-I school, you can get away with only having been starter for three years, all league/district for three, all state for one, and competing in state tournaments as well as national ones (source).

Anything less than that, and you're headed for Divisions II or III.

You'll also need good grades. You've got to keep your GPA at a 2.3 at the very least (source) and your combined SAT or ACT score will be taken into consideration as well. If you've got a 2.3 GPA, then your SAT Math/Critical Reading score is going to have to be 1080 and your ACT score is going to have to be 93 (source).

And don't think that you can get lazy with your grades once you're in: if your GPA drops below the minimum, then you're on the bench until your grades are back up (source).

You'll be able to keep your scholarship for a bit, but if you don't get your grades back up, you don't get off the bench. And if you don't get off the bench, well, what are you doing to really merit that scholarship?

You'll also need to get certification as an amateur athlete, which you can get from the NCAA Eligibility Center after you answer a fun questionnaire that'll ask you things about your pre-collegiate sports career. Have you had contact with a professional team? Are you represented by an agent? Will you be starting college a little late because of a huge competition? Now's the time to let the NCAA know that you mean business.