It's a test. And the usual advice seems appropriate:
Stop studying a day before the test and RELAX
Keep yourself a little short on sleep for a few days, so you will get a GOOD night's sleep the night before test day.
Eat a light breakfast, high protein.
NEVER change your first answer, unless you misread the question the first time
Don't obsess over a tough question, just move on to the next one - one of the later questions will usually give a hint about the 'toughie'.