Go over basic theory, of why things happen.
You seem to be good at maths, so you should get mechanics ok with some of the tricky rules that you have to remember.
Apart from the rules, equations are the main thing. AS Physics is literally plug'n'chug with equations. Find this and that and free marks!
The explanations are the hardest bits, but again going back to basic theory will help with this. Understanding why something works in physics is worth alot