1. Get a cheap 'scratch-sheet' notebook (newsprint paper is fine) and another second better higher quality permanent notebook.
2. Take messy shorthand notes using the scratch-sheet notebook -- write down everything you can, using abbreviations and symbols for words when necessary. Use whatever writing implement works best for you.
3. Right after class (or as SOON as possible thereafter) go to a quiet place where you won't be disturbed such as a cubicle in the main stacks of the science library. Sit there and transcribe your rough first notes into your final permanent notebook -- use a pen and print them legibly. Spell out all the words this time. Whenever you remember something the prof said that's not in your original notes, write it down, too.
4. Do this for each and every class (do not miss any classes!!)
5. The night before each exam, simply sit down in a quiet place without any distractions and re-read your final notes. Do this twice if you can.
6. Go in and ACE the exam.
Something about the hear-it, write-it, then see-it, remember-it and copy-it sequence magically reinforces neural connections, hard wiring that material into your brain and making that lecture a part of you. Preparing for an exam is as simple as going over your notes once or twice. You will find that you don't have to "cram" for exams and you will get "A's."
I worked out the above method during the early 1960's, long before powerpoint and the internet. Several of my students in the 2000's have adopted the following modification of my sure-fire method: print out the powerpoint presentation before class and bring it to class. Using a pencil, jot down notes alongside each slide. Then, as soon after class as possible, print out another copy of the powerpoint presentation (note that these are often changed right before each lecture, and the prof also deletes slides that were at the end of his presentation if he didn't get to them when they are placed at the beginning of the next lecture). Sit down in a quiet place and transcribe your rough class notes over onto this new copy, expanding them as much as possible using extra pages as needed (try to write down everything the instructor said). Then, study these notes right before the exam. You will find preparation for exams much easier and you'll get much better grades if you do this.