You know. I am not from zhong guo. So, I don't really know the level of the studies there. But I can give you some tips.
1. Physics and Maths are connected. Learning maths will greatly help you to learn physics.
2. Physics is understanding. Do not remember the formulae. Instead, try to learn how to derive them and learn why the formula exists!
3. Maths is all about understanding too. all the formula in maths are just to give you a way to quickly get the answer. So, if you understand how the formula was derived, then you will remember it easily.
4. Physics and Maths is interesting!
5. Chemistry needs memorization. This is because you would need to remember the chemical formulae and the standard unit and so on. But Chemistry will be easy once you get all the basics memorized. Chemical Equations are extremely important by the way!
That's about it!