The University of Minnesota provides the following tips for those considering applying.
Firstly, you should have started preparing in High School with STEM courses and AP courses. Gain real world experience through observation of patient care and procedures in dental offices, labs and clinics. You should have at least 100 hours of shadowing in multiple clinics. Have a range of volunteer experiences over a length of time, showing care in the community. Show that you have leadership and organisational skills, and the ability to work with a variety of people. You should also look into pursuing research experience. Try to take diverse courses at undergrad.