If you find you are struggling, (wo)man up early. There are resources available to help you succeed. In classes I tutored, without fail a couple people would come up to me right before the final and say they haven't passed an exam all semester and need a 98 on the final to pass, and to please help. On the other hand, the ones who came after the first or even the second exam, there was time to correct deficiencies and they were able to do well.
Don't take shortcuts. The best prep for step 1 is learning everything right the 1st time, so when that time comes you are refreshing, NOT re-learning.
(If your curriculum is systems based, ignore this one) It won't seem like it initially, but later classes do build on ones before it. If you don't know physio or biochem, pharm is going to suck. If you don't know histo or physio, path/pathophys is gonna be rough.
Don't compare yourself to the rest of your class. You can only control yourself, so why bother worrying about what you can't control?
Find out how you study best. Textbook, groups, repetition by yourself, flashcards, class, office-hours, etc etc. Do this as early as possible.
A select few can cram the weekend before and be fine. Statistically, you most likely are not one of them. Study daily and stay reasonably caught up. If you are learning new concepts the day before an exam, you're doing something wrong. You should be picking up the last little bit of detail.
In general, the material is not difficult. There's just a lot of it.
DON"T COMPLAIN. 1) It's annoying and 2) all your classmates are in the same boat as you. Same time commitments, same tests, same notes. I had classmates running around pre-block complaining about this and that. I'm convinced if they took all that time and energy and put it into studying, they would have done much better. And just to reiterate because I think it's important... It's annoying and makes no one want to be around you!
Find something you enjoy and make time for it.
Make friends. Classmates. Undergrads. Craigslist. whatever. Just search for some of the whining, lonely posts that show up here every couple months or so. You don't want to be that person. "I'm shy/Introverted" is not an excuse. Medicine is a social profession. Get used to it earlier rather than later.
Everyone says it gets better. I'm a resident now and still waiting for that piece of advice to be true. The only guaranteed good part is 4th year after interview season. The rest is variable from person to person.
Good luck