The responsible traveler should always look to protect local communities:
Always try to use local services, rather than external tour companies and services.
When booking accommodation, think about staying in bed and breakfasts or locally ran hotels and hostels, rather than international names.
Eat where the locals do, not only will this give you a better insight to the cuisine of the area you’re visiting, but it will also help to support the local economy.
Always respect local laws and customs. Not only is it illegal, and could result in serious fines or imprisonment, but the effect outside influences on a community can be devastating.
The introduction of drugs to the hill tribes of northern Thailand is a notorious case, where travellers taking drugs created a previously unheard of economy in buying and selling drugs.
As locals emulated their visitors, soon many communities became not only dependent on drugs themselves, but also as a means of survival, by selling them to travelers.
Buy locally made crafts and artifacts direct from the source, i.e. local markets and shops rather than from hotel lobbies and airport departure lounges where little of the original money will go to the community.
In short, help the local economy of developing countries by buying local produce where all purchases can be put straight back into the local community, in preference to imported goods and externally ran services.
Always question establishments where children are working, consider whether they should be in school or not.