When you study, don't just read over your notes or read the book. Everything probably makes sense when you read your lecture notes, but when it comes time to regurgitate that information on the test, you might not be able to reproduce it. You have to actively reproduce what you know from memory - constantly test yourself to see what you know and what you don't know, and go back and keep doing it until you get it all down and know it like the back of your hand. Come up with your own "test questions" that you think might be questions that will be on the test, and master those answers. Study with a friend, quizzing each other. Draw out the concepts/processes on a whiteboard, all from memory, don't cheat. Most importantly, whatever you do, study AHEAD of time. It is sooo much better to spread information out over a week or even 3 days than to try and cram it all into one night. Information gets solidified in your brain when you sleep, so if you can study and then sleep multiple nights before a test, the information you studied will be greatly cemented in your brain because of those multiple nights of sleep they have had. These are study methods that have helped me improve my academic performance.