Before putting up posters please ask permission otherwise
you can be sued for littering.
In quiet venues the best place to put up is on a prominent
notice board, in busy venues like discos the toilets are
a good option when people have a minute to spare while doing the business.
It usually a good idea to put up the poster yourself rather than
depending on somebody else who may be too busy to do it.
Unfortunately posters put up generally only stay up for a
week or two on busy notice boards.