Study the concepts and when you're in study groups, if you can explain it to someone, you should be fine on the tests. My API class had 4 Marines total, and we would get together all the time (or at a minimum, the night before a test) and go over everything. Some were struggling with the theories (especially aero) and I was able to explain the material to them a little differently than the books, which helped out both of us. If you can't teach worth a crap, pay attention in class (had a buddy that got the academic boot for generally not paying attention, and he was a 1000+ hr regional pilot) and rehash everything with your peers. You should be fine.