Okay, I'll admit it...throughout the course of my college career I had a total of 11 roommates.  Roommates moved in, roommates moved out, I changed dorms, I moved off-campus, you name it.  During all of the rearranging and attempts to forge new friendships (not to mention trying to maintain existing ones) I learned a few tricks of the trade that I wish I had known before blindly entering the belly of the dorm room beast. 

1. DO NOT live with your BFF - Before going to college I had been told by numerous people to never live with someone that I was already friends with, and now I can say with certainty that they were absolutely correct.  Living with two of my best friends destroyed our friendships.  Now, we are only acquaintances.  Just because you love hanging out together doesn't mean that you will enjoy living together.  Living together, especially in a dorm room, requires cleaning, and limited living space.  Trust me, even if you seem to be getting along in the beginning, the friendship fall-out isn't far behind.  
2. COMMUNICATE - I will illustrate this tip with an example.  I once had a roommate who INSTANT MESSAGED me about the fact that we needed to talk about living together while I was sitting two feet from her...literally!  At the time I was living in a suite with 3 other girls (we had our own bathroom...WOOT!).  There we were...all sitting in a row at our desks working on homework and such, and she IM's me about the fact that we all need to sit down together and "talk."  I am not going to give specific advice here, because I am no master communicator, especially when it comes to talking to other ladies, but please, please, please, don't IM.
3. Designate time -  Designate specific times during the week for cleaning, inviting people over to your room, quiet, etc.  And stick with them!  If you and your roommate decide to allot time between 8:00pm-10:00pm on weeknights for quiet and homework, and your roommate decides to bring her booty call over to bump uglies during said time then SAY SOMETHING!  It is your living space too!  
4. Socialize together - This is especially important if you are thrown into a living situation with someone that you haven't met.  Invite your roommate to lunch, to dinner, or to an event on campus that seems interesting.  If you feel that you and your roommate have different interests invite your roommate along to an activity that you enjoy, and tag along to an event that she's into.  Don't compromise your values to go do keg stands if that's not what you're into, but open yourself up to new things.  Bonding with your roommate outside of the confines of the dorm will create a more comfortable living situation, and possibly even forge a new friendship.  
5. RESPECT one another - This one is particularly important when it comes to each other's stuff.  Ask to borrow your roommate's shirt.  Don't just take it from her closet, wear it, and put it back covered in beer stains.  More often than not people are willing to share their belongings.  Violating this rule will ruin any chance for a civil living situation right out the gate.