While grades and MCAT's are the often the two most important factors its important to realize that's not all. College should be an opportunity for you to take courses outside of your major and experience new hobbies and interests. Take advantage of the opportunities and use them to add personality and character to your application.
Research is a big deal.
If you are interested try getting a position in a respectable lab or even your university. Keep track of all publications resulting from your research. Be confident but not cocky at the interview. Its important to remember that you can lead the interview in which ever direction you want. So if you want to highlight certain aspects of your application lead the conversation in that direction.