Learn how to read your roommate. I’m not talking about mind reading, just saying that if you’re living with someone, you should try to get to know him/her better, observe their habits and reactions to certain situations so that you might sense a good or bad mood brewing. Then you may decide whether you should stick around for more or run for the hills as fast as you can.
When you sense a storm coming, the best thing you can do is take a walk. Don’t let yourself dragged into senseless arguments, wait until things calm down and then talk it out! It’s very important not to leave things unsaid, but most frequently disputing over stuff when you’re angry doesn’t have the best results.
That being said, don’t let things fester and don’t make them personal. Address issues that you see and allow your roommate a chance to improve. If they improve, make sure to thank them for putting in the effort and you appreciate it. Same thing on your end, what might not be a big deal to you could be a big deal to your roommie.
Set some ground rules and stick to them! Decide who and when does the cleaning of the common areas; set a “party frequency” policy unless you want your apartment to turn into a frat house with people coming over every night; and most importantly be specific about sensitive stuff like utility payments dates and splitting costs of common necessities.
Remember that the secret of happy living is not in the intensity of the experience but in the balance, order, rhythm and harmony!