It's not sitting down for too many hours and running your eyes iver the course material. What have worked for is as follows. 1. Read it to get the concept, don't worry about remembering it, just focus on understanding it. 2. Make short notes, if you can on your own words regarding the concept you just figured out. 3. Then try to remember what you studied without referring to your notes, this way it gets stored in your mind, reading again and again doesn't work, trying to actively remember what you just read is the way to go.