Mistakes here can make you sleep poorly, therefore need more sleep, feel tired and then depressed. Skipping sleep, food or exercise in order to study, work or party will make getting sick more likely. Don't follow the group on this one. A good diet and exercise can relieve depression, but sugar, alcohol, and over-eating worsen it. Live on campus, if possible.
Students often consider only rent when working out the cost of a place to live.
Dorms may seem expensive when you consider you only get half a room. Problems here include shopping for and preparing meals and spending time and money commuting. The more subtle aspects are feeling disconnected from what's going on and feeling more responsible for roommates and their happiness, social life, health, and problems. It may be that living off-campus just makes it harder to hang around for all the activities or to get back to campus for social events, interest groups, cooperative studying, and socializing. Or it may be that it just seems easier to put in more hours at an outside job since you are off-campus anyway.