Here are some guidelines for responsible travelers. When you visit another country you always change it a little bit. So try to make a positive contribution. It makes you feel good and is the only right thing to do.
Use energy and water sparingly. Recycle everything you can or else take your waste back home with you (batteries and other toxic items).
Get to know the local customs. Be culturally sensitive, especially with photography. Always ask before photographing people. Often just pointing at your camera will result in a bright smile and a nod. If you promise to send people their photos always do it, otherwise don’t promise.
Don’t give anything to beggars. This just encourages more poor people to leave their homes in the countryside and move to slum-areas in the big cities. If you want to help, give money to a local charity or school etc. You can also donate to well-known and respected charity like the International Red Cross/Red Crescent or UNICEF when you get back home.
Never buy anything from children. They should be in school or playing, not selling or begging. The money you give them often goes to their parents to support drinking or drug abuse.
Realize that people in the area you visit often have time concepts and values different from your own; not inferior, just different.
Help the local economy. Stay in small family-run hotels and eat in private restaurants. Try to buy handicraft directly from the artisans, not from the lobby shops in big hotels.
Don’t get involved in drugs. Drug-related organized crime undermines the whole society with corruption. Also many people in developing countries look up to you so don’t make drugs seem a sign of prosperity to them.