Odds of Getting In
If you have two hands, an artistic bent, and your hobbies include carving your family's likenesses on lavender soap, you're most of the way there. Many people who get into sculpture do it after trying some kind of "real" job, like banking or teaching or astrophysics, and coming to the conclusion that they'd rather make art with their hands.
Since this is a creative pursuit, the best thing you can do is practice, practice, practice. That means art school, workshops, and mentorships. While perfect isn't something you necessarily need to strive for, better is always a useful endeavor.
If you want to do more than sell low-priced goods at town markets, you're going to need a portfolio as well (source). The portfolio is a small booklet (and nowadays, website) that includes sample photographs of the best of your various works, for perusal by prospective patrons, employers, and galleries.
Think of this as your visual résumé. If you want your phone to ring, it better be impressive. And definitely don't include that "experimental" project from junior year in high school. No one needs to see that crap.