Concepts, theorems and formulas in textbooks should be memorized on the basis of understanding. Every time you learn a new theorem formula, try to do an example without looking at the answer to see how much you can master. After you finish, you can compare the answers and see what the result is. Even if you are wrong, it will deepen your understanding of the theorem. You will apply what you have learned in the process of doing the problem in the future.
Specially sorting out a wrong book, collecting your own wrong questions, and recording the usual exams, tests and wrong questions are often your own weaknesses. It is also the most important knowledge. When reviewing, this wrong book has become a valuable review material. In the exam, you will encounter similar problems, which will be much easier.
To learn anything, training is essential, let alone changeable mathematics. After finishing the homework assigned by the teacher in class, you should usually do more exercises with moderate difficulty, which can deepen your understanding of the content. Of course, don't fall into the misunderstanding of boring questions, be familiar with the questions you will encounter in the usual exams, and be comfortable in training and combine work and rest.