Lay a good foundation first in summer vacation and read more books (mainly based on functions). 14 and the finale often have function problems. It is often related to the derivative of your sophomore year (often the finale). As for improving your own level, you should usually find your own topic material after school (personal opinion L), don't do it during recess (this is inefficient), and grasp the time of self-study at night. I usually just want to spare at least half an hour for math practice (which is very important). When the foundation is OK, you will find it much easier to pull it up.