Landed an internship - what now?

Came from a normal public high school, parents are doctors, got into a semi-target, and got an IB internship (GS, MS, UBS). What should I do to help with the following:

• getting the return offer (already reading news, gonna do some excel stuff before summer)
• PE/publics recruiting (i feel like reaching out to headhunters is OD rn)
• overall career trajectory (deferred MBA stuff? looking for in-semester opportunities?)

2nd-year student, STEM major doing decent in classes and being involved in clubs. I'm definitely enjoying college, hanging out with friends and going out, playing sports, etc. I'm unsure between MF/UMM PE, growth, and crossover.

Just want ideas/advice from ya'll on what I should do with free time that could help - thanks lads.