To live happily with roommates, you have to come to agreements on the lease and share responsibility. You decide when and how rent will be paid. You talk about whether people may sleep over, whether it must be limited to family or best friends or whether they can each bring home someone they met that night, and how long anyone can stay and whether they should let the housemates know. You decide how common areas will be maintained, by schedule or other idea. You all agree to not touch other people’s food or drinks or laundry detergent, and who will wash dishes.
You decide whether there can be parties or not. You decide whether towels and sheets are to be individually washed or communally.
You talk about music and whether there will be cable tv or netflix. You don’t live with adults with rules, but simply respect and agreements.
You should make sure people are who they say they are by checking on social media.
There will be unforeseen issues, but respectful friendly people deal with these things.