-Highlighting, taking notes, etc. straight in your book
-Recording lectures
-Buying A & P coloring books/other workbooks for the classes you take, and working on the parts that are emphasized in class
-Talking to yourself (in the privacy of your own study space, of course) - I usually do this by reading my notes, explaining diagrams/drawings in the text, etc. to my stuffed animals. I'm not much for study groups, but this works for me really well.
-Study groups with actual people, if that's more your thing
-Take whatever practice tests you are given or can find
-Go through study guides and figure out which parts you know; then go back and write down only the answers you didn't know - thsi helps you avoid wasting time