Keep Your Room Clean | Surprisingly Keeping your room clean is a lot easier in college! However, this does not mean your room will never get messy. You should keep your room clean because one, who doesn't love a clean room, and second, its just courteous to your roommate. No need to have her tripping all over your things when she is heading to the bathroom or walking out of the room.
Be There for Her | Your roommate may get homesick, and this is totally normal. The best advice I can give is to be there for her. Let her talk it out, give her space, anything she wants. Just be there for her in general, be her friend!
Lock the Door | Whenever you are the last to leave the room be sure to lock the door. You don't want someone coming in your room without asking or even worse have someone steal something important!
Be Friendly | In some circumstances you may not get along with your roommate. That does not mean you can be rude to her! ALWAYS be friendly and don't snap at her. Even if you do not get along, you can still be friendly :-)
Give Her Alone Time | For most of us, college is the first time we have to share a room. Therefore, we sometimes just need alone time. Give your roommate the alone time she deserves. Go to the gym for an hour, get some food, anything to give her at least a little alone time.
Be Courteous | If you are on your way to dinner ask if she wants to tag along or get her some Starbucks, if you stop. My roommate even sometimes makes my bed if I'm at class (best roomie ever? YES)!!!
Communicate | If something is bothering you, just tell her. It will be better for you to tell her so she can fix whatever is "annoying" or bothering you.
Ask Before Use | JUST ASK! Chances are she will say yes. I borrow my roommates clothes all the time and all I have to do is ask! This is just being considerate of their things. You don't want her taking your things without asking, so just ask permission.
Cleaning Schedule | Personally, my roommate and I keep the room pretty tidy, but the cleaning schedule comes in handy with our bathroom! I have a suite style dorm which mean I share the bathroom with my roommate and two other people. Our cleaning schedule consists of taking out the trash, making sure there is toilet paper in the basket, etc.
Let Her Nap | Naps are honestly one of the best things ever, and no one wants to be disturbed while napping. Therefore, if your roommate is napping, just try to be quite and not wake her. You can even turn the lights off if you don't need them on!