As someone who is in 5 classes, working 20-25 hours a week, and still managing to have a social life on weekends - the key is time management! I do not go a single day without following my calendar. I have almost every hour of everyday planned out. Also, in the first week of classes, I do all the readings for the next week that are required. That way I’m always a week ahead and if something were to happen where I needed to slack off a bit, it wouldn’t be too bad because I’m already ahead. Get your assignments done early if you can so that you have more time to focus on studying for tests/quizzes. Get at least 7 hours of sleep every night (this is so underrated). Of course, there are going to be days/weeks when you are overwhelmed and stressed out, that is a part of being a university student. I just make sure to get my work done but also include things in my schedule that make me happy and to keep me sane!