1. Give your brain a rest the day before the test.
If you study enough prior to the then, then there is no reason to attempt to cram more information.
2. Make sure you're on pace to finish the test.
If you are halfway through your exam time, and you're only a quarter complete, you probably won't have enough time to complete the entire test. Make sure you get the easy problems, skip the harder ones.
3. Take the time to answer the questions correctly.
This is a balancing act between answering too fast and completing the exam. You may be answering problems too fast and may make a small error that will give an incorrect answer; if you are done with your exam early, take the time to recheck your work.