Do what the professors tell you: buy (or download for free) the books, do all the practice exercises and proofs, go to office hours, listen to the professor in

Do what the professors tell you: buy (or download for free) the books, do all the practice exercises and proofs, go to office hours, listen to the professor in class and don't write everything they write, just the key stuff, and get together with other students to go over the harder problems. That'll get you through the courses, and your level of effort and capabilities will determine how much you learn. Forget about grades, if you just do your best you'll get the best grade you can.