You both are individuals and should be treated with respect. Spats between both of you may occur, but work through the problems, understanding the reasons. They make people unique and interesting to get to know on a deeper level. Try to get to know your roommate. You would want your roommate to do the same.
Good communication is the key to having a great roommate relationship.
If you share, always re-supply. Then there is no miscommunication. Don't try to win every argument, disagreement, or checkers game. Sometimes it's best to just let things go. Try to stay neutral, since the angry feelings may not last.