Everyone is different. Different methods work for different people; the following are only suggestions on improving upon your current studying techniques.
It is best to review the material right after class when it's still fresh in your memory.
Don't try to do all your studying the night before the test. Instead space out your studying, review class materials at least several times a week, focusing on one topic at a time.
Have all of your study material in front of you: lecture notes, course textbooks, study guides and any other relevant material.
Find a comfortable and quiet place to study with good lighting and little distractions (try avoiding your own bed; it is very tempting to just lie down and take a nap).
Start out by studying the most important information.
Learn the general concepts first, don't worry about learning the details until you have learned the main ideas.
Take notes and write down a summary of the important ideas as you read through your study material.
Take short breaks frequently. Your memory retains the information that you study at the beginning and the end better than what you study in the middle.
Space out your studying, you'll learn more by studying a little every day instead of waiting to cram at the last minute. By studying every day, the material will stay in your long-term memory but if you try to study at the last moment, the material will only reside in your short-term memory that you'll easily forget.
Make sure that you understand the material well, don't just read through the material and try to memorize everything.
If you choose to study in a group, only study with others who are serious about the test.
Test yourself or have someone test you on the material to find out what your weak and strong areas are. You can use the review questions at the end of each chapter, practice tests that the teacher may give out or other pertinent materials.
Listening to relaxing music such as classical or jazz on a low volume can relieve some of the boredom of studying.
Don't study later than the time you usually go to sleep, you may fall asleep or be tempted to go to sleep, instead try studying in the afternoon or early evening. If you are a morning person try studying in the morning.
Also see: How to Study