Phil Miller has a quote about how to study, from Tyler Cowan's latest book. Since my students have midterm exams on Thursday, this advice is apt: do problems; make sure you can do problems; answer questions; anticipate questions.
The point is this: most people do not study very effectively. They study to feel they are trying. They study to feel better about themselves. They do not always study to succeed in their chosen field. They spend hours staring blankly at sheets of paper and nodding about what they understand. Students should spend more time trying to solve problems or answer questions, usually under simulated exam conditions and with a clock ticking. Tick, tick, tick... that's the way to go, and yes, the whole point is that it hurts.