I can’t believe I’m actually saying this, but I have to: Go to class. The single most important predictor of how well you’ll do in school is to actually show up.
Can you date without showing up for the date? Can you get paid for work without showing up for work? Heck, no! Similarly, you can’t learn if you’re not there. And no, you’re not going to be to learn everything on your own by getting the notes or reading the book. You need to be in class to absorb what you need to absorb.
Avoid the temptation to let any small distraction keep you from class. Don’t skip class unless you’re ill or face a family or other emergency so severe that missing is unavoidable. Do notify the prof if something like this happens and you must miss.
Go to class. That is all.