From my experience, it seemed that everyone came up with their own system that worked for them. Some people never took notes in class, just listened in lecture and remembered what they heard. Other people would read textbooks from cover to cover. Some people just read through the notes 4-5 times and memorized them verbatim.
Personally, I'm a visual learner, but I tend to zone out if I'm passively reading through notes. So I developed a system where I rewrote the class notes in a more succinct form as I studied them. If two lectures overlapped, I would think through the best way to combine and assimilate the information. It took longer than just reading through them, but somehow I learned things so well this way that I just had to glance through the notes again the night before the exam and I was set. (Some exceptions were Biochem, Anatomy, & Micro. For those, I used a white board to write things over and over in the days before the exam.) This is also nice b/c if you save your notes, they are a good resource for future reference. You can look back at them and recall things more quickly than using a textbook.
The most efficient way to memorize? Integration. For every fact you are trying to force in your brain, try to associate it with something else you've learned. I found I didn't have to rely on rote memorization for lots of things because they overlapped with things I'd already learned, or I knew the underlying basis for them. There will still be isolated things you have to memorize (and more things seem isolated at first when you don't have as much knowledge with which to integrate them), but at least there will be less of them. (This is a hard concept to explain so if it doesn't make sense let me know and I'll try to think of examples.)
Good luck and enjoy the rest of your summer!
