Hey there,

Whether it is Mathematics, Physics or any sort of subject, first and foremost you need to built a strong foundation of that particular subject.

How can you do that:

1- Learn it from scratch.

2- Focus on basics.

3- Deep learning of topics.

4- Practice as many questions as you can.

5- Revise weekly (Saturday and Sunday).

So if the basics of an individual are clear, no matter what sort of question arrive he/she is capable to solve it, However if you get stuck in any question try to solve that question again and again, hit an different approach to solve it.

If after trying so many times, even using different approach if the question is not solved then go for the hint only you will be able to solve that particular question.