Being polite goes miles in Milan, a city built on etiquette. "Grazie" and "Piacere" (a pleasure) will be your most useful terms. Tipping is not required, and should be modest at most. Hotel porters and cleaning staff should be tipped. There is no need to tip taxi drivers. Public transportation is great but most Milanese use BikeMi, Milan’s city-organized bike-sharing initiative that anyone can sign up for—daily, weekly, or yearly. If you happen to hear "cortili aperti," stop in your tracks. Milan's very best secret courtyards, in the city center and surrounding neighborhoods, are rarely opened to the public, with a single Cortili Aperti event happening in late spring, usually with a last-minute announcement.