To get good marks in JEE main physics you need to understand concepts very well and cover all the syllabus because the question cover all the topics there for you should you attention to all the topics also don't forget to solve all the previous years questions as it will help you in understanding the importance of various topics.

For JEE advanced you need is sound analytical and numerical skills to solve the physics problems also some problems involved in depth understanding of the concepts therefore you some good books I would recommend you to go for HC Verma it is one of the best book for engineering entrance exam cover all the questions you can leave questions which require a lot of calculation but not concepts and don't gobar ability questions also the best source of practice question is the previous years questions and also don't leave question made by go to the answer.