First, I want to commend you for being a full-time student and working part-time! It is not easy to do and you have a lot on your plate. I have a few recommendations for you:
(1) Find a class and work schedule that works well for your style of studying. What I mean by that is that some people do really well in having back-to-back commitments such as class from 9 AM - 2 PM and work from 3 PM - 8 PM, while others prefer large chunks of time in between commitments to allow for relaxation or study time. Figure out what rhythm and cadence allows you to feel the most productive.
(2) Get organized! Whether it's keeping notes for yourself in your phone, writing things down in a planner, keeping an online calendar, or anything else, make sure you have a way to keep on top of all of your commitments. Learning how to be organized helps ease the stress and also allows you to make sure you carve out time to relax.
(3) Make sure you make time for something you really enjoy. Whether it's joining an organization or picking up a hobby, taking care of yourself is very important when you have a demanding class and work schedule. Don't forget to make time for yourself and your happiness!
(4) Ask for help when you need it. Take advantage of resources on-campus such as Academic or Career Advising or tutoring centers. These resources exist to help you and since you have so much to juggle, finding and knowing about resources that will be helpful for you will help you in the long run.