I use business cards, @Trina-L0. The only contact information on them is the listing URL, both written out and in QR code. I don't want people trying to get in touch outside the system - that happens enough already.
It is helpful when someone is interested and wants to look the place up when they get home, that sort of thing. I have left some at local businesses that have asked. I leave some in a holder in the treehouse, and some in the main house entry. I go through them very quickly.
I used a posterized photo for the style of it, and to cut down on numbers of colours. I don't include the Airbnb bélo because I don't know the legal implications. Easier just to avoid it.
Hope this helps. Here is a scan of mine.