A very solid academic performance, while you should aim for high grades in all courses,
science pre-requisite courses play a large role. Many schools look for students with
at least a 3.5 GPA.
Scoring highly on health professions admissions tests (MCAT, DAT, PCAT, GRE, etc.).
This not only demonstrates command of the subject material, but also indicates ability
to succeed on tests "down the road," including professional licensing examinations.
Volunteer experience, including a substantial amount of exposure to the profession
of interest. Professional schools expect or require this!
In general, experiences:
Should show that you work well with a wide variety of people (leadership is good)
Should show that you like to help people (philanthropies)
Should show that you have learned about the profession through clinical experience
with patient contact, informational interviews with practitioners, etc.
Excellent letters of reference. It is important early on to make genuine connections
with your professors, and advisors.
Well-prepared applications, including essays.
Apply Early and be mindful of deadlines! Make sure to look into specifics because
they vary between programs and schools.