Most effective thing in order:
3. Downloading past trial papers from various schools, CSSA things (for yr 12) and past HSC papers from BOS. Buying good work books such Creelman, Success One, and other past paper books / practice questions by topic. You should select questions you struggle with upon reading it, and skip the easier ones that you can do in your head (certain 1-2, sometimes even 3-4 markers, and certain multiple choice Qs). Personally, I don't like Excel books and study guides are not very effective.
1. Make your own study notes (using various text books and stuff from school), using other people's notes if you're stuck and cannot find a way to incorporate the information into your dot points.
2. Downloading sources off the internet and memorising them through reading (as most people who proceed to use this method do) by far the least effective thing to do as it doesn't show your understanding, or may differ to yours. Good for cramming or pure content based subjects (Ancient History) I guess..