Okay.... I have been a roommate in several scenarios and my dad has been a landlord/owner with roommates under several circumstances.
I lived in five roommate situations in my 20s:
1) Acquaintance rented two bedroom cottage from landlord (who lived in other cottage on same property) and I moved into the second bedroom after she'd been there for awhile. Awkward for many reasons. Main lesson learned: Get to know an acquaintance better before living together; don't assume you'll do well together just because you have some things in common. We had plenty in common (good/average things) and yet she was addicted to men with bad habits and she didn't know how to budget and/or pay the rent and utilities on time. I paid her since I wasn't on the lease, so I was out the money when the power was cut off. The landlord was easy-going, so rent wasn't an issue but it was late all the time and I felt very uncomfortable with that.
2) When the above roommate's boyfriend broke into our house (with me in the house on the phone with 911) for his drug stash, which I previously had no idea existed, I decided a stranger would be infinitely better!
This was before online avenues existed, so I used our local off-beat paper (limited readership vs only major paper in major city) to find a single woman offering a room in her home. I found a woman 10 years older than me who owned a two bedroom two bath condo. I instantly felt safe in her condo and around her. We had a terrific roommate situation for a number of years until she fell in love and her boyfriend moved in and then they decided to get married and raise a family. The three of us got along great, too. They needed to sell the condo in order to buy a house in a family-oriented neighborhood. The main lessons learned here: a) Trust your instincts! b) Work out details like cleaning, cooking, laundry BEFORE you sign a lease. She had this in writing for me to see before signing a lease and paying a deposit. I could live with her rules easily, but some friends thought I was crazy. c) If you do end up going with a "stranger", do a phone interview first. I ruled out a ton of places based on that alone.
3) When the wonderful situation above was ending (with ample notice and consideration), I decided I wanted a little more control over my residence. This time, I used the same resource (off-beat paper), but looked for a more equal partnership. I found a single woman roughly my age in a two bed two bath apartment where her current roommate was moving for a job. All three of us met and we all liked each other. (The roommate who was staying was going to have to move if she didn't find a replacement, so the outgoing roommate was still there. I was fine with meeting them both. I could have done it differently.) This situation was perfect for about a year when she met the man of her dreams and moved into his house (ample notice). We were both on the lease and were responsible for half the rent paid directly to the management company. I don't recall how the utilities were set up, but we each had our own landline phones (my dad is an electrician and did this for me in the above condo and taught me along the way). We had a perfect blend of "togetherness" and alone/private time. We hung out together at home and went out to dinner and clubs sometimes, but we had our own circles of friends.
4) When the above roommate let me know about moving in with her boyfriend, I decided to find a new roommate and stay put. I put in an ad in the same paper I had always used, plus I sent emails to everyone I knew for friends of friends, etc. I ended up with a male roommate whom everyone liked. (I didn't meet with him alone. He invited me to his then-current place to a party with some friends of mine.) We had a great time being roommates! We threw Academy Award parties (his big thing) and pool parties (my idea) and probably spent the most "together" time of any roommate situation, but still had our privacy. We isn't gay and neither am I, but we never were attracted to each other in a romantic way. Main lessons learned: a) Don't be afraid to try new things. b) Look for what you want, but don't expect it in the same ol' package. This man kept our apt as neat as I did and we never had to discuss a thing (after the initial chit-chat about housecleaning standards). He was the most hassle-free roommate I ever had on many levels. c) Trust your instincts and take people with you when you are not comfortable meeting a new person.
5) So, as luck would have it, the above perfect roommate situation was ended when a good friend of mine was moving across country and he had the best set-up ever and was inviting me to take over. I have known this friend since my 17th birthday and we had a long, complicated history. He is a good guy, though, and he promised me I'd be happy. I trusted him. I moved into a house by the beach and shared the house with a widowed grandmother. I had my own wing of the house, closed off by two doors (one from living room and one from laundry room) with three bedrooms and one bathroom. I had exclusive use of two bedrooms and shared use of the kitchen, laundry, bathroom (in my wing), garage, and backyard. For most of the time I lived there, the empty bedroom was a guest room and rarely used. I was able to use it for my mom and dad (separately) and my aunt. My housemate used it for her grandchildren. I only paid rent and my own phone here. No utilities. We had no heat or A/C, which was fine, and she didn't want to deal with shared bills. I set up the smaller room as my bedroom and the larger room as a studio: small sofa, small dining table, desk, etc. Living at the beach was really, really fun! Main lessons learned here: a) It is hard to go from equal control/partnership to living in someone's owned property where they also live. It wasn't a BIG deal or I would have moved, but it is important to note it was a lot easier for me before I had the equal partnership roommates. b) You never know when situations will change. My housemate retired during my time there and she needed more money. She raised my rent a reasonable amount and then got another roommate for that third bedroom. I went from basically having my own wing, including easy, private access to the bathroom, to sharing the hallway and bathroom...with a man I didn't like.
I moved out when DH and I met and fell in love and decided to get married.
I'm adding my dad's experiences now. My dad found himself all alone in a rented house, stuck in a lease, due to our family falling apart. (He created the mess himself, but did finally take positive action towards bettering himself.) He found random roommates to fill all three bedrooms (except his) and put up with a lot of crap in order to save enough money to buy his first house in CA. (He had owned homes in Colorado 7-8 years prior.) He learned the hard way.
When he purchased his house, he went about finding roommates in new ways and mostly had good roommates. He owned and rented out rooms for 15 or so years. The best situations for him were men who were in that area (Bay Area) strictly for work. They pretty much stayed during the week, working all day, and then going elsewhere most weekends. Sometimes, he had roommates who worked with him and they'd carpool and save time and money. This was during the Silicon Valley boom and his house was in a good location. He made good money sharing his house and he became financially savvy along the way.
The worst roommates he had were the friends he took in like stray animals. He unwittingly enabled their existing issues and they sucked him dry until he finally wised up and kicked them out. (I can think of at least two such "friends", but there may have been more since I didn't live in that area.)
He was forced to retire early and he waited a year or so before selling that house at the height of the boom. When he moved down here to be close to me (only child for all intents and purposes and his only grandchild), he was able to purchase his house outright and he has since purchased two places in a retirement community in AZ (one condo and one single-level detached home). He rents out the places in AZ to snowbirds and visits himself during late spring and late Fall (tolerable times there, weather-wise, on either end of his renters' contracts). He lives here otherwise and doesn't have any renters here, but he did take in one "stray" for a period of time. That didn't last long, thank goodness.
He chose his properties well in AZ. The condo had a regular tenant for certain months and the previous owners had a few tenants over another few months. Dad contacted them all and had new contracts worked out for everyone's benefits. His rental income for the condo (5 months) completely covers all his expenses for the entire year. He has a plan to sell this place and make a profit.
The house had regular tenants for the typical snowbird months and Dad contacted them through the management company to inquire about staying on before he even decided to purchase. They worked out an even better deal all the way around. Dad stays here now when he goes to AZ, so he doesn't want another tenant. He could get one and completely cover his expenses, as with the condo, but he chose to enjoy this place and pay that opportunity cost. He really likes the retirement community where both places are located and may end up moving there more of the year.
He communicates directly with his tenants because he had years of experience already. Most other homeowners in this development use a management company. They offer roommate finder services, too, not just tenants.
Best wishes! I hope all this jabbering helps you in some way (or someone else)!!!