For example, you can promote the tourisme of many ways, like cleaning the streets, creating work, creating a website with local information, being present on social media like Facebook, Twiter, Youtube because nowadays most people use Internet. It could also promote through advertising on televisión.
Take something insignificant and boring in the town and pretend it's a big deal. It worked for Brussels: https://en.wikipedia.org/wiki/Manneken_Pis
Alternatively, lots of drugs and prostitution seem to attract tourists as well, at least they did for Amsterdam.