The best way to study for any type of exam at any level is to start by learning as much as you can about the exam itself. What type of questions will the exam include - multiple choice, fill in the blank, problems to be solved, short answer, true/false? Knowing the format in which you will need to present answers may influence the way in which you review the material to be covered by the exam.
When reviewing the content for the exam, consider creating an outline. Make each major section of the information a main point of your outline. Add details and examples as subtopics under each major heading of your outline. Include tables, diagrams, illustrations that will help make connections between important facts as subtopics. The information for your outline should be drawn from class notes, lab results, textbook or other reading materials, and any other sources of information presented during the unit of study being covered by the exam.
Use your outline as a tool to review and test yourself. If you can't explain why one topic is important or how it affects other aspects of the material, spend more time finding and learning information about that area. Don't leave this until the night before the exam - give yourself at least a week to work with your information, compile your summary outline, and insure that you know and understand the information it organizes.