Need some help with A-Level planning

Alright, so, hey there, I'm David,I study in Sri Lanka and I'll be sitting for the A-Level examinations in 2018.
So, basically, I'll be starting classes next week, and I'll be taking 3 subjects
Combined Mathematics(so...Pure+Applied)
Physics
Chemistry

Since the school is a bit far from home, I'll be boarding and I'll be having after-school classes as well...(Sri Lanka exaggerates with "tuition classes",as they call them, which are basically private institutions where you go after school,to learn the same stuff you do at school,but prior to it)

So, okay, I'll stop messing around, what I need from y'all are just tips and advices...whatever you can give me...On how to properly study during A-Levels, Where I should give my priorities, and study guides and revision time tables for the above subjects.

I really appreciate it if you've read this far.Thank you!

PS-It would be awesome if you could give me some good advices on how to improve my mathematical skills and brain power(I'm not that bad)

To be completely honest, there is no such thing as 'properly' studying for your A levels, its more about whether your revision techniques work for you as a person or not...

I normally, rewrite my notes after each class, using my textbook to sort of become accustomed to a certain topic. Flashcards/youtube videos etc can also be extremely helpful, especially if you find a particular topic difficult.

Maths is basically all about practice, the more you practice, the better you will get