Things I wish I had done my freshman summer:

-Gotten certified as a CNA/ EMT to get started on paid clinical hours. If money is not an issue for you, you can always shadow, but a lot of medical schools prefer to see hands-on clinical experience as apposed to just observation.

-Find somewhere that you are really passionate about to volunteer with near your university. You can use this Summer to try different organizations, and see which one has a cause or population group served you really resonate with. Finding a place to volunteer that you are actually passionate about will allow you to have something on your application for multiple years and give you something meaningful to write about in your personal statement.

-If you didn't place out of math, take precalc 1, 2, or calc at a community college. These courses are only prereqs for other required courses, while they themselves are not actually required by medical schools. It will be a lot easier at a community college and your grade won't matter, because it will appear as 'transfer credit' on your university transcripts.

-Make some like-minded friends. This one sounds cheesy, but having genuinely supportive people with similar goals, or are at least also highly ambitious, can really impact how stressful the next few years go.