The person you choose to live with can have a major effect on your quality of life. Everyone's got a horror story about a seemingly nice person who turned out to be the Roommate from Hell. So, how do you avoid these walking disasters?
Research. You need to ask a lot of hard questions before you sign a lease or move in. Make sure you both agree on money issues as well as what kind of lifestyle you want.

Know your limits. Before you start your roommate search, you need to know what you can live with and what you can't. Don't assume that just because someone is a friend, they'll make a good roommate -- you have to be compatible.

Screen them. Once you've found a good candidate, run a credit check, verify their job details, check references, dig up what you can online (including their Facebook page).

Agree on the big stuff before you sign a lease. Make sure you agree about things like who pays what each month, how you'll divvy up household tasks (cleaning, food shopping, cooking, etc.), what are your noise limits, rules for overnight guests, etc.

Communication is key. Don't go in with your head down and eyes closed. Be aware of who your roommate is!!!