Asides from knowing your syllabus, knowing your calculations and the completion of past papers.... which everyone knows about...
1. Remember the pracs that you have done at school, they can be tested. It's part of the syllabus. So PRACS.
2. Know your QUESTION VERBS (how to answer a describe, an outline, an explain, a discuss, an evaluate/assess question, etc.)
3. Have a good night's sleep.