If you're serious, you've gotta take your LSAT. Register for the October test (administereted September 30th this year) and start studying for it two or three months in advance. I only had a month to study before I take mine on June 12th, and that's really hurt me.
If you use the LSAC site to view ABA school data, you can get figures on minorities at particular schools. Most law schools have single digit numbers for Natives and, as such, being one can't hurt you. Growing up on a rez means you've been through and seen (and eaten
) things that most other people couldn't imagine and that makes for a great diversity and personal statement. Just be sure to keep it upbeat and not to focus on the things your situation deprived you of, but rather what it provided to you and how the wealth of your experience can enrich the lives of your law school colleagues.
Two things you have to do: get a bachelor's degree and take the LSAT. If you've got a few years to go before you get your degree, consider pounding on the books to maintain a really high GPA before diving into LSAT. Being an URM, having had an unusual upbringing, and a high GPA can combine to do wonders. Play to your strengths and show your dedication in your grades. If you do that I think you've got a shot at going as high as is possible.