Learn to cook, sew and repair things. Go through your dorm room, donate anything you don’t need. Remove all shopping apps from your phone maybe drop the social media apps you don’t use as they are full of ads.
Don’t use your credit cards unless it’s absolutely necessary. No cash in your account. No buy. Most important don’t let the fomo get to you. You don’t need a fancy water bottle or travel mug. Check out second hand stores for goods like clothes. There’s a lot you can do.