Make a weekly schedule and devote a certain amount of time per day to studying. This will improve your grades also. That amount will vary depending on whether you're in high school, elementary school, or in college, and also varies by field of study.
Study in 20-50 minute increments It takes time for your brain to form new long-term memories, and you can't just keep studying for hours at a time. Take 5-10 minute breaks (but not more than that.) Then, do something physically active to get your blood flowing and make you more alert. Do a few jumping jacks or run around your house, play with the dog, or do whatever it takes to burn some energy. Do just enough to get yourself pumped, but not worn out.
Find a Good Study Spot
You should feel comfortable, but not so comfortable that you risk falling asleep--a bed isn't a very good study spot when you're tired! The place where you study should be relatively quiet (traffic outside your window and quiet library conversations are fine, but interrupting siblings and music blasting in the next room are not).
As far as music is concerned, that's up to you. Some people prefer silence, others prefer music in the background. If you belong to the latter group, stick to instrumental music (music that has no words like classical, soundtrack, trance, or some celtic) and that you're already familiar with (not something that's bound to distract you). Having the television on while you study is a bad idea.
Clear your mind.If you’ve got a lot on your mind take a moment to write yourself some notes about what you're thinking about before you start studying. This will help to clear your mind you focus all your thoughts on your work.
Snack smart while you study. Have your snacks prepared when you begin a study session--don't wait till you get hungry and go rummaging for food. Avoid any snacks or drinks that will give you a rush of energy, because with every rush comes a crash in which all the information you studied is lost to an intense desire to sleep. Focus on "slow release" carbohydrates, which not only give you a steady stream of energy, but they also boost serotonin, a brain chemical that makes you feel good:
Rewrite your notes at home. When you're in class, emphasize recording over understanding or neatness when you take notes. That doesn't mean you shouldn't try to understand or organize your notes at all; just don't waste time doing something in class that you can figure out or neaten up at home. Consider your in-class notes a "rough draft" of sorts. Rewrite your notes as soon after the class as possible, while the material is fresh in your mind and so you can fill in any gaps from memory. The process of rewriting your notes is a more active approach to studying--it engages your mind in a way that just reading the notes doesn't.
Learn the most important facts first. Don't just read the material from beginning to end, stopping to memorize each new fact as you come to it. New information is acquired much more easily when you can relate it to material that you already know.
Make Flash Cards. Traditionally, this is done with index cards, but you can also download computer programs that cut down on space and the cost of index cards. You can also just use a regular piece of paper folded (vertically) in half. Put the questions on the side you can see when the paper is folded; unfold it to see the answers inside. Keep quizzing yourself until you get all the answers right reliably. Remember: "Repetition is the mother of skill."
Make associations. The most effective way to retain information is to "tie" it to existing information that's already lodged in your mind.
Make it a Group Effort. Get some friends together--friends who are actually interested in studying, that is--and have everyone bring over their flash cards. Pass them around and quiz each other. If anyone is unclear on a concept, take turns explaining them to each other. Better yet, turn your study session into a game like Trivial Pursuit.