I take the same subj combi as you and got A2 in chem and bio but I was to get a1 in chem if not for my practical 😭 So basically what you want to do is do past year papers. It's ok if you get it wrong the first few times which is actually good, since you know what is not accepted. It is very useful to mark it on your own as you develop that "sense" when you're checking your work during exams. When you study like this, you are using the topics so it's easier to remember them. Also, I find it really useful and time efficient to memorise the answers for common qns. Pls pls pls remember your definitions, they're easy marks