Think about it. If you studied mathematics in junior high school, what would you study in senior high school? What did you study at university? So first of all, don't be afraid. Mathematics in junior high school is actually basic knowledge, but it is very vivid. For this reason, you must first fully understand the content of the textbook. There are very few knowledge points in junior high school, which is easy to summarize. Pay special attention to the preconditions of definitions and theorems, because those are often test sites. Remember, mathematics is a tool, and it is only a tool. Doing a problem is like solving a problem. Only by firmly grasping the tools can we be comfortable.
The second step is to do more questions. Contact with various questions and test sites.
The third step is the most important, and that is the summary. Where is it easy to summarize, where is it easy to set traps, and where is it easy to create difficulties? Then summarize the methods and ideas to solve the problem. Of course, all this is based on the first two points.
Come on, I still like doing math problems in junior high school best, because math in junior high school is like a brain teaser, which is very interesting.