Obviously we all know when visiting an area that we are just that: visitors, and that we should behave accordingly.
Always respect other cultures and their manisfetations. Beware that local people may express themselves differently to what you are used; other people laugh about things which are serious matters to us and vice versa.
Never get angry when you are on holidays, because it only worsens a negative atmosphere. Always try to find a friendly solutions, even when you really feel you receive a bad treatment. There are always channels to ventilate your complaints in an (more or less) effective way. Some people are all too ready to criticize other cultures, while they should ask a little more and try a little harder to get know better a local population.
Supporting local projects (schools day centres etc.) is always a good thing, but remember, that this support is temporary and therefore not sustainable.
Behave well in public-the "don´t do things and remember that there are heavy jail sentences against sex with under-aged. In Latin America all people over 18 yaes old carry a personal id-card with them.Keep in mind that you are not the first person to visit an area and that you will not be the last either. Sustainable development is a process of giving and taking and you have to be grateful just as well for having new experiences.