As a student majoring in mathematics, I can only tell you that there are three main lines in mathematics during the undergraduate period: analysis (the starting order may be slightly different): fraction-real change-functional-complex change-ordinary differential-partial differential-probability theory and mathematical statistics algebra: high generation-extraction-number theory-deviation-graph theory geometry: how to solve it. Learn a few points as long as you can understand them. You don't have to get high marks. Unless you want to get a scholarship, you will use it in a series of courses in the future. I recommend you to read Wu Jun's The Beauty of Mathematics. It doesn't matter what you don't understand the first time. Go through it first, and you will come back to see it unconsciously after class.