I did Ancient History accelerated so I'm guessing this will apply more to SOR II than maths advanced, but I thought I'd pop in anyway.
What really helped for me was making sure I was up to date on all my notes. Having all those syllabus dot points out of the way already while everyone was...
essentially just get ahead on your study resources, so when exams come around you can spend all your time studying instead of making notes and flashcards and whatever
I only had one subject last year (ancient history), but I just made sure I'd caught up on all my notes from term 4 (which was super useful down the track for exams)