Do what works for you. Nonetheless, here are some general test-taking strategies. If you panic when you first get your exam, during the exam, or at its end, just take a minute and relax. Remember that one grade never makes or breaks you. Carefully read through the exam in its entirety before you start writing.
Many students fail to answer the correct amount of questions or to correctly apportion their time.
When you read the whole test carefully, you'll figure out which questions to approach first. Do the questions worth the most first. If all questions are equal, it doesn't make a difference which one you do first, but at least you know what to expect. Carefully read through the exam in its entirety before you start writing. If there's some material you're worried about remembering, perhaps a list or a formula, look it over right before you go into the exam, and jot it down in the margin of your test or blue book as soon as you sit down.