Everybody has got a different "learning style". Consequently, everybody has a different "studying style". But the way that you're studying right now might not be the best for you.
How would you know? Simple: If your grades are not what you would like them to be, then you probably have to modify how you study! I am going to give you a few suggestions on how to study effectively. They worked for me when I was in high school, college, and grad school. Given that everybody's learning style is different, a few of my suggestions may not work for you, at least not without some individual adjustments.
All the same, I recommend you to try them. Many successful scholars use them (or some slight version of it). read here www.examssuccess..com