For most courses, most of what is on homework and tests are discussed in the class. Take good notes, copy the diagram your teacher draws on the board to remember the information and if there is something you need to find easily, use highlighters. If you want to be more creative with your notes, use colored pens which are fun to write with, but use them only for sections that you feel are important.
Wasting nights over books and feeling like you have gotten nothing out of it is the worst thing to do, instead put all important ideas from your textbook in your notes and go over it till you feel like you remember the material well.
It is a lot easier to retain when you review the information out loud rather than going over it in your brain, and it is more effective to have someone testing you on your study guide. To make studying fun and easy, have a friend over, make flash cards or join an after- school homework club; do whatever you can to make sure you know the material.
Participate in class to show that you know your stuff, besides it is a good way to cement in your head what you have learned from doing your homework.
Though it is a bit more stressful than when with a friend, but this way you are covering all your bases. Your teacher will also appreciate it when you participate in class and you will get treated better.
If you are struggling with the coursework or you are not sure what is required for a good grade, ask your teacher for help after class. If the subject is too hard for you to understand, get a tutor to explain things to you in a manner that you can understand better.