Having a regular practice schedule will help tremendously while in music school. Make sure to make it realistic, especially at the beginning when you are adjusting to being in a high-stress environment. Two hours a day, five days a week, is plenty at the beginning. Make sure to take a ten-minute break after the first hour to let your mind digest what you just worked on, and to eat something. You can slowly adjust the practice schedule, adding more time as the semester goes on, building in ten or fifteen minute breaks as you extend the time.
Music theory and music history are both subjects that can be difficult, especially at the freshman and sophomore levels. Forming study groups for both subjects early and meeting once a week will help take some of the pressure off and enhance the learning process as well. Music theory entails written work and ear training as well. Meeting to work on ear training, and quizzing each other on intervals and chord types is a great way to review material leading up to exams.
The advice "Ask for guidance when you feel that you need it" can be applied to almost any college course of study; in music school, students can feel as if they are supposed to just know what's expected of them, or know the ins and outs of whatever lesson material they are studying. Make sure to ask whenever you have a question in lessons, ensembles and classes. Once you have the correct answers, you can then work on lesson pieces correctly.
Music school doesn't always include a music business or "Life after Music School" course in its major requirements. If those classes are available, be sure to take them and ask lots of questions on how to make a living once you are outside the comfort zone of music school. If those classes are not available, make sure to ask your professors and music-school guidance counselors for career advice. Also, emailing professional musicians where you live with questions about how they support themselves and what career opportunities are available to the musician is helpful as well.