Renting by room is a great strategy as long as you know what you're getting into. To manage common spaces, I suggest a) house rules b) hiring cleaners who comes by once per month so no one feels like they're being told what to do. Also helps to provide some communal things like soap, toilet paper, paper towels, etc.
The more effort you put into screening tenants, the better. Each house is going to have its own "feel" and you don't want people coming in who will rock the boat. For example, what are you going to do about people who like to party? Or smoke? Or people who work at night and need the area quiet during the day? There's lots of extra things to be aware of which you wouldn't normally need to deal with. But the extra cash can make it worth it.
