Test taking habits and techniques have taken up entire books. Some universal ones that work well are diversify, practice, and review.
Diversify. You should not only study what your teacher or curriculum tells you to study. It is better to read beyond what it required of you. Wikipedia is a great resource for such exploring. This allows you to form a more comprehensive knowledge base and something you learn in the process of studying for one test will aide in studying for another.
Practice. Practice truly does make perfect. Taking practice tests under test taking conditions allows you to be ready when the real day comes along. Practice tests help you identify your weaknesses and gauge where you stand. It is important to keep track of your time, as most tests are time sensitive.
Review. It is important to review the mistakes you make more than it is important to know what you know. You should use practice tests and lectures to identify you weaknesses and strengthen them. It is always better to know your weaknesses rather than your strengths.