Location: Where you live, where your family and friends live, where you would like to live.
Stats: Their avg MCAT compared to your score. Their avg GPA compared to your GPA.
Reputation: The school. Primary care or research focus; Known for a particular specialty that you have an interest in (i.e. Pediatrics); Well-known for good residency placement (i.e. Ivy league or Top 10 school)
Using those tools, you should make a list of schools that are "safety", "maybe", and "reach". Remember those will be your opinion and not fact because you might be surprised of the outcome. For example, I didn't get an interview to one of my "safety" schools, but I was wait-listed at one of my big "reach" schools.