The two things that were super easy, but I just didn't realize the importance of the first two years were applying early and applying to enough / the right schools. This year I really researched what schools were looking for before I chose 15 schools to apply to. Also, I got my application, all my LORs and transcripts in on the first mailing, which helped me get pre-Dec. 1st interviews.
I also tried to improved my application by taking more classes (and acing them), continuing to get dental experience (dental assisting, helping in a dental lab) and volunteering a lot.