If you are into taking photographs, Indians Tarahumara provide great subjects for some terrific shots. Unfortunately they generally don't like to be considered subjects for your photographs, would you if someone treated you as a tourist attraction? The Mexican Government recommends asking for permission when taking photos, respecting the right to privacy by the Tarahumara people. They are quite and gentle though, and if they realize your camera is pointing at them, they just turn their face away without leaving or yelling at you. Please be courteous and respectful and don't insist in trying to capture their faces.
Please be responsible. Do not encourage begging. This creates a much larger problem then your short trip allows you to understand.
Children are encouraged to stay in school. But if they receive money from all the rich gringos they quit school and stop listening to the bread earner of the family.
Want to help? Buy a basket from their mothers. (I came back with 22 baskets)
Learn a little about the indigenous Tarahumara either before you go or while you are there. Their culture is fascinating. They have an annual race which is barefoot through the mountains for days - a feat I can not even imagine! They are also a poor people now with famine supposedly getting worse. We bought thier crafts to support their culture and gave the children gifts of pencils, crayons and paper. They are a proud, quiet people and deserve respect. It is polite to ask their permission before taking thier photos.