Obtain an undergraduate degree in art or the humanities. An art form like sculpting requires a concentration on technique. Learning these things outside or inside class will be key to getting admitted to a graduate program.
Hone your skills with sculpting, and prepare a professional portfolio. Because sculpting is done with many materials, and in many sizes, a good quality portfolio with professional pictures of your art work will suffice.
Search through different programs. Instead of basing your decision on locale or ease of admission, look for a school that will give you what you need to grow as an artist. Look for how much studio space each student is given, and how many different genres you can study.
Take the GRE. Not every school will require this test, but it is never a bad idea to take it for the ones that do. In order to get accepted into an MFA program in sculpture you must have all of your materials ready for submission well ahead of time.
Apply to different schools. You may want to keep the number of schools to a minimum, but it may be harder to get into an MFA program in sculpture than some other studies. Any art program is going to have a lot of competition.