If you can, try to get A+'s in your exams. That usually helps.
In all seriousness, never think you're too good. There was a guy at my school who was doing alright in his sacs, I guess, and he kept going on about how accounting and methods, etc were a cakewalk for him in our spares. He ended up with 50 something. On that note, don't just rely on your teachers. Use other texts besides the ones listed by your school. Seriously, if I didn't do physics in year 11, spesh would have been an epic fail. SAC marks =! Exam marks. Just because you're averaging in the 90s in your school SACs doesn't mean you're entitled to the same in exams. Look at past VCAA papers, as well as other trial exams, and accompanying solutions/reports. Get a feel for the structure and type of questions. Doing them helps, too.
That stuff is only sorta useful if you went to a school like mine where SACs are basically spoon fed (at least in the subjects I did). Just trying to say that school standards aren't always the same as VCAA ones.
Do not burn out. I don't actually know how to fix this, but it isn't any fun. It happened to me at the end of first semester. It got to the point where I couldn't do any work at home, not even revise for sacs. Luckily though, I managed to scrounge enough motivation to get through revision period and exams. I think economics is what caused the turnaround. My eco teacher is a really slow marker, so by the time we were up to our third outcome, he hadn't even finished marking our first. When we finally got them back, I didn't get the highest mark (after being on top for a year and a half, only to get beaten by a short asian girl with thick glasses is NOT cool). The possibility of coming second was the kick in the pants I needed, I guess.
Oh, and try to get some good sleep the night before exams. I got around 3 hours for both my english and bm exams, and the last half of both were not fun. I tried to compensate with energy drinks and coffee (for English), but all that happened was me yelling at everyone before it started, and me being dead and repeating the same stuff halfway through.
Anyway, good luck to y'all!