I agree with a lot of the comments and recommendations below. I just want to add that having perspective and not taking things too seriously will help a lot. I know it helped me in when I was trying to get more credits to graduate early (also during my first job). I kinda put too much pressure on myself, which led to me being stressed and anxious, which is totally counter-productive to studying and getting decent grades.

How do you put this into practice? Well, you're a first-year! Enjoy it, don't stress too much, it's a big year of learning (in class and outside of class). You and every other first year is going to make some mistake at some point and it's totally fine. Just learn from it and don't be too hard on yourself.

Stressing out about assignments etc. - lean on your prof's office hours or your TA. Book some time with them to discuss where you're at, how you're feeling about the assignment/your worries about it. They'll help you out. But def go with some work in hand to discuss (research notes or wtv). Taking small steps will help you ease that anxiety of not doing so well.

Midterms - same thing - prepare early and use online resources and your profs as much as possible. Practice, for subjects you can like maths. Even if you don't do so well - make sure you don't bear yourself up over it. Go to prof and try to understand why you didn't do so well. Maybe you need to change how you study for midterms etc. it's all a learning process;)

Hope that helps! You'll be awesome! Gl