What are some good tips for college students who want to stay healthy during school?

Many ways! Having a child in college, i can certainly relate to this excellent question. Some tips include: 3 healthy meals a day, exercise regularly, participate in intramural sports, lots of hand washing, stay up to date with immunizations (especially the meningitis vaccine, ) and maintain a proper balance of study and extra-curricular activities.
Don't smoke! Smoking causes many illnesses including heart disease and many types of cancer.