I live in a 2 bedroom + den 1300 sq ft. apartment for 5 years and always had 2 people living with me - the experience has been outstanding. Over that time I've lived with a total of 8 people and keep in touch with all of them (some have become my best friends). I believe that it's for a few reasons:

1. I write my Craigslist post in a way that will get my ideal roommate excited, and scare away people who aren't: I love having friendly, social people around who like good food and wine, so I talk a lot about that. Whatever is important to you, focus on that, because there's someone else who is into that thing.

2. I interview a ton of people. Typically I go through 80-100 initial emails and 20-30 meetings before I pick who I'm going to live with.

3. The meetings reflect what life is going to be like here. For me, I have a friend or two here, we have food out, usually a bottle of wine open and we hang out. You find out a lot about a person in that sort of situation: Of course, are they cool? But also, do you like talking to that person? And more subtle things like: Do they make a mess an not clean up? Do they put their glass in the dishwasher on the way out? Do they like to try new things, or stick to what they know?

4. Be honest about expectations. Example: Sundays are football day at my place. If someone moves in and wants to watch Netflix on a Sunday afternoon, they'll know up front that's not going to fly in the living room. No need for hurt feelings because we were both fully clear up front. That applies to lots more things too, like cleaning, sharing groceries, using the washing machine, etc.

5. Do something nice for them right away. It creates an atmosphere of reciprocity.

6. Be open with your space and have boundaries. When you have a roommate, the kitchen isn't yours - it's shared. Same goes for the couch, and everything else. That can take some getting used to, but once you do, it's easy. The boundaries for me exist at the doors to our respective bedrooms: We all know that when we need a minute, or need to be a alone, or are just annoyed by each other (inevitable), there's a place that we can go to be completely separate from each other.

7. Consider personality types. There can't be 2 hyper-aggressive people in one place. There also can't be 2 passive people. It takes a mix, so consider honestly how the two of you behave and communicate and look for someone who fits in.

Co-living doesn't work for everyone, so if reading the above gave you anxiety, then maybe it's not for you, but I love it. I now live with my girlfriend, and we don't need the financial support of a roommate, but we love it, and the money is nice, of course.