Perhaps the single most-abused social custom in Mexico is the use of shorts. Mexicans rarely wear them outside the home or off the beach, while many foreign travelers seem to have packed nothing but. There is a bit more flexibility in beach areas, but if you’re venturing inland or into smaller communities, it’s worth getting in the habit of wearing long pants or skirts whenever going to dinner, attending performances, and especially when entering churches and government office, where shorts and tank tops are definitely inappropriate.
Topless and nude sunbathing are not customary on Mexican beaches and are rarely practiced in Cancún  and other areas frequented by Americans and Canadians. However, on beaches popular with Europeans, especially Playa del Carmen  and Tulum , it is more commonplace. Wherever you are, take a look around to help decide whether baring some or all is appropriate.
No one enjoys having a stranger take his or her picture for no good reason, and locals—indigenous or otherwise—are no different. The best policy is simply not to take these photographs unless you’ve first asked the person’s permission and he or she has agreed. Tip: If the potential subject of your photo is a vendor, buy something and then ask if you can take a photo—you’re more likely to get a positive response.
Even a small amount of Spanish can go a long way in showing respect and consideration for people you encounter. Make a point of learning basic greetings like buenos días and buenas tardes and using them in passing, or as preface to a conversation; it is considered somewhat impolite to launch into a discussion without greeting the other person first.