Go over fundamentals, make sure you can explain different biological processes. Such as fossilisation, immune response and the different lines of defense, etc. Go through the Biology FAQ on the VCAA website -- has some good information on what you need to know, and what you don't need to know. Be wary of traps in the multiple choice, make sure you've eliminated the other answers before moving on. If you don't know, move on and come back -- there will be time. Go through last year's exams and see what was answered poorly, they are likely to ask those poor ones again (and I'm expecting a photosynthesis/cellular respiration question in the short answer, as there strangely wasn't one of those last year). If it's a two marker, add some detail to your response, but don't try to show off in your answers. Make sure you fully answer the question: if it says explain then link your response back to the question!
Most importantly, when you are stuck on a short-answer question, especially in those questions where they give you a hypothetical question go back to what the previous parts have asked and see if there are any links. In other words, try and remember what part of the study design they are trying to test. That saved me quite a few marks on the exam. Good luck.