All great advices, but I'll repeat them:
-Time management. Do the homework given/assignment on the same day. Don't cram for an exam. Specially if it's prereqs for dental school. You will be thanking yourself that you have solid foundation for DAT, thus have higher chance of scoring higher score.
-It's ok to take a break from school. You don't have to take classes just because everybody else is taking. Specially if in one term, the professor rating is very low (ratemyprofessor), don't be forced to take the class. It's ok to skip a term. Or if you are going through rough times.
-Stack your ECs (shadowing, volunteer, research). The sooner, the better.
-Study hard when you have to study, and play hard when you play.
-Develop a solid study habits, enjoy college life.
-Keep high GPA no matter what.
-Search scholarships.