I have once piece of valuable advice for you that I wish someone told me about. Do past papers. As many as you can. Your school is likely to ask you questions that have popped up in past papers. I waste so much time this year studying every single little thing , and even for prelims.......and i feel like 99% of my studying has gone to waste FML LOL ):
past papers for the win. you can dl them here, or i can just send you my file ^_^
i want to go to usyd, since that's the only place that i've actually visited HAHA.