I agree with Bashwell, spaced repetition (I used Anki) is invaluable. Overall, I haven't seen any great resources for med school study strategies (I'm actually working on creating one now, for this exact reason) but I think that a combination of asking your school's student support staff, talking to M3/M4s who did well on Step 1, and being honest with yourself about what worked and didn't work for you in UG will get you pretty far. Beyond that, a lot of it is just on the job training - like when they start bombarding you with reading and quizzes the second week, you'll adjust quickly.
Remember to be flexible and try new things during your first few months, too. It's better to stumble a little at the beginning and find something that works for you rather than continue doing something that doesn't work for the whole year.