I'm not too fond of rules and always try to be as flexible as possible, but seeing as I have had problems before, here are the four commandments to my apartment :

1. DO NOT LITTER. It seems to me that it is the principle of airbnb that guests should treat their accommodation as someone's home because it is exactly that : my home. So when you pay for a night, you do not pay for me to pick up your garbage, dirty tissues or used tampons around my home (not kidding, I've had people leave disposable hygiene items with all sorts of bodily fluids on them). As a matter of fact, I wouldn't even take a supplement for that, because I don't want anyone's garbage or bodily fluids around my home in the first place - and there's a rubbish bin in litterally every room in the flat. I know it seems obvious to most people, but the problem occurs more often than you would think.