You just need to start with the basics, remember that you can't do all the test sites for each question, and then classify the test sites, such as the derivative test here and the series test here, and classify the problem-solving process, such as changing elements to solve series problems, such as trigonometric constant transformation series.

I don't suggest sorting out all the problems and wasting time. When sorting out the wrong questions, you can sort out the types of knowledge points and problem-solving processes.