Get some good rest the night before, take a deep breath, and do NOT get ruffled if the "right" answer isn't one of the choices - sometimes it isn't there and you will get at least partial credit no matter what.
The trick is to read the questions carefully - take your time there as they can be worded to make you -think- they're asking for one thing when they're really asking for another. And don't second-guess yourself - I always found in practice tests that the ones I went back, over-thought, and changed were the ones I got wrong; the first answer was far more likely to be correct!