I agree with the above. I've done quite a few mathematics/statistics units at uni now, and the study regime is essentially the same. You can't rote learn your way through it all. Application is the key.
The more practice questions you do, the better you will become. Don't just do the easiest questions in the book. Try a range of difficulties. Some from the textbook, some from a past VCAA exam even that are relative to the topic(s) of the SAC, or some that you might feel even a bit uncomfortable doing.
Check your answers in the back of the book, and if they're wrong, try and figure out how they got that answer and you can learn the faults from there.
But yeah, as I said.. Do heaps of practice questions, varying in difficulty. It's really the only way to expose yourself to potential scenarios in a SAC/exam.
Good luck