Firstly, realise that you will need to change your way of living in order to accommodate a roommate. Chances are that you are used to living on your own, and having your own space. However, the introduction of a roommate into the mix means that things are going to be a little different, and all will not always go your way. However, it is best to view this as a positive change – living with a roommate is bound to help you break out of your rut, and become less rigid and more accommodating in terms of lifestyle.
Understand that there are certain common spaces you and your roommate will be sharing, such as the kitchen, bathroom, living room, front yard and garage, etc. Thus, these spaces need to be kept clean and orderly at all times – do not expose the other person to your mess, and if you really need to throw your stuff around, keep your mess limited to your own room.
Coordinate with your roommate to lay down explicit rules regarding cooking and cleaning in the house, as well as chores such as laundry and washing dishes. Choose what you will be doing for the house as a whole, and which chores both of you will be doing individually. Paying bills, and shopping for food are also matters that need to be chalked out explicitly, in order to avoid confusion, inconvenience, and any arguments and fights.
Hold regular roommate meetings (keep an easy to remember time, like every Wednesday at 6pm), in which you will both discuss house matters, and any concerns either of you might have. If there are any problems, or any anger on either side, do not prolong this or let it fester – talk it through immediately, and resolve issues as they arise. Air your concerns, and give your roommate a fair hearing too, without getting angry or defensive.
Keep your bad moods limited to yourself, and do not bring them home or take them out on your roommate. If you have had a bad day, make sure you cheer yourself up before you get home. Do not throw things around or bang doors in anger – remember, you are sharing the space with someone else.
Finally, make sure you appreciate your roommate, and do not consider them a burden or an inconvenience. Remembering that they are helping you in times of financial constraint will help you remain grateful for their presence, and ensure that you behave kindly towards them.