Do not smoke indoors unless you and your roommate smoke and are agreeable to smoking in the living quarters. Smoke can trigger an allergic reaction in a person with chemical sensitivities. It also discolors white items and leaves an odor. Best advice: Smoke outside, even if your roommate says smoking is not a problem.
Never clip your nails in the living room or bedroom, and rinse your hair down the drain after you shave. No one enjoys discovering the discarded hair and nails of others. Clip your nails in the bathroom, over the toilet or a trash can, so you can catch and easily dispose of the clippings.
Maintain social lives apart from one another, even if your roommate becomes your best friend. Keep your socializing at a respectful volume level if your roommate is in the house studying or sleeping.
Pay your portion of the bills on time every month. Nothing can ruin a friendship faster than money-related arguments.
Ask your roommate if he would like you to pick something up for him when you are leaving the house to go shopping or grab a bite to eat.
Assume that your roommate does not want you to eat the turkey sandwich she left in the refrigerator. Keep your hands off your roommate's food, unless you have an explicit agreement regarding sharing. It is very annoying to find that food or a drink you were saving for later is gone, and this type of situation can quickly cause resentment. The same rule applies to taking or using your roommate's other belongings, such as toiletries or clothing, without permission.
Pick your things up from the communal areas, such as the kitchen and living room.
Talk to your roommate if you have a problem with something she does or does not do. When you first move in together, tell her you would appreciate it if she would do the same.