What I notice in students who consistently make A's is that they study every single day of the week, be it a weekend, a holiday, whatever. They study the least for exams on the night before, and they probably study less overall than other students. But the key is to start studying on Day 1 and to keep studying ever single day, even if its just for thirty minutes or forty minutes per class. If you are not already doing this, I can almost guarantee this will bring you to the high A level.
For example, lets say you have class Monday, Wednesday and Thursday.
Sunday night: pre-read Monday lecture, read the textbook for the lecture. Write any questions you may have going in to lecture
Monday: go to lecture and take notes. When you go home, go over the notes and try to quiz yourself in some way. Make questions or cover a part and recite it. For biochem, write out the pathway.
Tuesday: redo your review of Monday's notes. It'll be quicker this time. Pre-read Wednesday's lecture
Wednesday: go to lecture and take notes. When you go home, go over the notes and try to quiz yourself in some way. Make questions or cover a part and recite it. Pre-read Thursday lecture
Thursday; go to lecture and take notes, et cetera. Go over wednesday's work.
Friday: Review Thursday material
Saturday/Sunday: Pre-read Monday's material et cetera.
Next week: corresponding to each day, go over last weeks notes and do the same thing. Now you are practicing spaced repetition and will be MILES ahead of the competition just by doing this alone.