Here are some suggestion I can give: focus on what had been taught in class so you don't have to study something extra. If you don't understand anything, just ask the professor until you understand all the problems. Most of the people fail because they over look at all the easy problems. Make sure you done all the homework, and repeat it if necessary. Also on the personal note, keep your body healthy by doing exercise, work out to let your body relax. Because your body also had its own limit. Overall, just do everything you can to make sure you got all the material and understand of what being taught in class. Then at least you won't fail or might be doing well. Good luck!