1. Don't care about how you look.
I swear I lost out on so many theatre parts because I would spend auditions obsessing over how awkward I looked or bad I sounded. Nobody cares and you're only going to do worse if you freak yourself out. This applies to life in general too, because until you let yourself be free you're never going to enjoy yourself.
2. Don't care about limitations.
Upperclassmen will try to scare you from a good place out of taking certain challenging classes or professors. Young me, I cannot tell you enough how subjective limits are. By the time I was a senior, I took the most challenging classes and I tell you there was nothing to be afraid of if you worked hard. So take the classes, all the classes, the hardest section of each class and challenge yourself because if you put your mind to it, you cannot fail.
3. Listen to your body.
When your gut tells you something is wrong, do something. If you feel like you need help, but everyone else tells you you're fine, get help anyways. If you want to press harder and explore something deeper, whether that's a medical issue or a problem with your friends, do it. It never hurts to take precautions, but it can hurt to wait too long.
4. It's okay to be alone.
There will be times you will have the whole world with you. There will be times when nobody will be by your side. Either way you'll be fine and it's for the best. You'll find doing things just to keep people by your side A) isn't going to work and B) is trying to hold on to the wrong people. When you try to hold on to the wrong people, both the wrong and right people will leave you, so do what's right and trust your judgement. Being alone will not hurt you, it can only help you reflect and grow.
5. Never give up.
It will feel tough, but in these long 4 years you will end up in the most wonderful place with the most wonderful people who are all rooting for you and, having accomplished and overcame so much, you will be content.