Okay, so I have heard third-hand about some incidents of Doors following people. Like, wherever they move, they find the Door waiting for them. Waiting for them to open it.
So when they go to a new place, they draw doors on the walls. I don't know if this actually stops a Door from manifesting (probably not), but it can't hurt. I've seen chalk doors drawn on alleyways and spray-painted on the side of buildings.
Of course, like the Operator Symbol, drawing a door may just attract a Door to you. I don't know if the City likes fucking around with people, playing with its food, but that third-hand report I heard contained an anecdote where a chalk door was erased and a real Door manifested instantly. So, hey, draw your own conclusions.