Don't talk about sea tactics. At this time, you should ensure the quality of every question you do and do it together.
It is not recommended that you buy questions with many questions and few answers. It's best to sell some with detailed instructions. The more detailed, the better. You have to pay attention when choosing. You have to see if you can do that problem. Did you do it? If you can, don't buy what the teacher said, just buy some books that are usually wrong-loving, not too difficult and moderately difficult.
You can also buy some special exercises. If you are not good at geometry, buy special exercises for geometry.
You can try to do the real questions in the senior high school entrance examination and practice various choices. Wait until the comprehensive ability is enough, and then practice in sets.