For maths I basically just studied ahead trying to do all the cambridge chapters a bit before our class went through them, but also I did a whole bunch of past trials papers before our 3rd assessment task and trials this year. Honestly I found the cambridge 'proofs' for most of the concepts in...
My schools only ranked around 60th so the competition was probably a bit weaker than yours will be, but I was able to improve my maths rank from ~80th after Y11 to 3rd at the end of Y12 (advanced only though) and my phys rank from 45th to 10th. So it’s very possible to have a large comeback in...