Space out your study time to help you remember what you study. This is called spaced trials and it is well researched. For example, if you are going to study for a total of 3 hours for a exam then you should study for 30 minutes per day for 6 days instead of 3 hours the day before the exam. You will remember much more information and for a longer period of time that way.
Use more than one sensory process while studying. For example, reading information will help you to learn it. To involve more senses, read it then make and review visuals (such as diagrams that you color code). Follow this with verbally summarizing the information then listening to it, which uses multiple senses. This will help your recall of the information.
Use study tricks, such as mnemonics. Do you remember "Please excuse my dear aunt Sally?" The first letter of each word (in order) represents the order of operations in mathematics. Each operation starts with the same first letter as a word in the phrase. It is easier to remember that phrase, though, than it is to remember "parenthesis, exponents, multiply, divide, add and subtract." You can use these tricks for long lists or to make associations. They will help you remember information.