Get pepper spray or mace and attach it to your keychain. You can also find alarms small enough to fit on keychains. Since you always carry your keys, you will always have these self-defense products with you if anyone tries to attack you. Keep them in your hand when alone outside at night because they will not be useful if you have to search through your bag when you need them.
Attackers typically look for someone who is distracted and not paying much attention to what is going on around them. If you are talking on the phone or reading emails on your Blackberry, you are making yourself more vulnerable for attack. Instead, know what is going on around you. Frequently turn around and check to make sure no one is following you and take note of what is going on in the path ahead of you. Being aware of your surroundings can save you from being attacked.
Although it might not always be possible, try to walk with others at night. If you have a night class, find someone who lives in your dorm or near your apartment who can accompany you when you walk home. If you are at a party, ask someone to walk you home if you want to leave before or after your friends do. It is much safer to be out at night if you are in a group than if you are by yourself, so act responsibly.
As a college student, you have a very busy schedule and it can be difficult to keep tabs on you. Make a point to tell your roommate, a friend, your significant other or your parents what your schedule is for the day. Before you head home, give them a quick call or send them a text message to say you are on your way home. If people know your whereabouts, it can help them to track you down in the case of an emergency.