First, work on your GPA and keep trying to get it higher and higher. With a 2.98 you have some work to do – you should aim for at least 3.3, but don’t lose hope. It is important to remember that if the national average is 3.59, then at least 50% of admitted students have GPAs of 3.59 or lower.
As for the mysterious formula, unless you ask them yourself no answer can be 100% accurate, but here is the breakdown that my preprofessional advisor gave me (you should ask yours for his/her opinion, if you have one at your school):
GPA/Curriculum: 25%
MCAT: 25%
Experience with Medicine: 15%
Personal Essay: 10-15%
Volunteer Work: 10-15%
Other Activities: 10%
In my personal opinion, you have to first make yourself look like a good candidate, but then in your personal essay and your secondary application essays you have to also make yourself interesting. Don’t leave important stuff out, but make them want to interview you. Nail the interview and you’re well on your way.