A/A* advice

I’m currently in Y13 doing aqa bio ( chem and maths aswell) with exams in june. I want to start revising from now but just don’t know where to start. Just for reference , I’m predicted and A and got A/B in most of mocks this year and last year. I understand all of the content but I have a problem in memorising it and I feel like I don’t know the content well enough. Do I go over content or do I just go straight in with past papers and just go from there . I’m aiming A/ A* and I’m willing to put a lot of effort into it. Any advice from previous students aswell would be MUCH appreciated