And people cant fucking seem to comprehend the concept of garbage cans and ash trays. Jesus fucking christ i have to come out and pick up garbage and cigarette butts every other day because people cant do this simple task. How does ash tray work!? How!?!?
Be creative, make a nice looking sign with a pictogram that shows a trash can with a green checkmark through it, and a pictogram with a heap of trash and buzzing flies with a big red 'X' through it, on some cheap white wood, with waterproof markers.
I did that last month, and so far it has worked excellent in stopping the ongoing dumping of trash and litter in my street. People had been dumping everything from carpets and matresses to paint and car batteries out by the tree near my front door for a few months. Half the street was complaining about it, yet no one seemed to be able to catch anyone in the act. Finally made me decide to put on my old creative hat and do some handiwork, screwed the homemade sign to the littered tree, and it has worked wonders. Not a single piece of trash to be seen anymore, instead of new mess twice a week. I guess someone got the message.
If you don't live in an immigrant neighborhood, you could use text I guess. Over in my neighborhood there's a lot of people who do not speak Dutch, so I went with pictograms just to be sure. I seem to recall that pictograms are more effecitve at manipulating social behaviour than written text is anyways.
I doubt it works for cigarette butts, or random small litter. It could help you with the garbage though.