Learn the culture, what's acceptable and unacceptable. For example, "almost half of all Japanese hotels ban tourists with tattoos from public bathing areas due to tattoos being common among yakuza crime organizations, although these bans are being reconsidered by Japan’s tourism agencies in an effort to boost tourism. However, they’re not the only country with tattoo bans. Thailand and Sri Lanka are cracking down on tourists getting Buddha tattoos while visiting due to cultural insensitivity." — From TravelAgeWest.com
Choose the Right Destination
Make informed choices when picking destinations. Learning about a country or area before you go, will help you decide whether it's the right destination for you. It will hopefully prevent unpleasant surprises, too. What will the weather be like? What foods are commonly available? Unexpected extreme poverty, political policies, and even hygiene practices of the locals, can leave some travelers shocked, baffled or stunned.
Do Some Homework
Travel isn't just about the sites, but the people, too. Aside from the usual guidebooks, government websites are good places to start researching a country's people or destination, and hundreds of foreign news sites can be found at online. Not surprisingly, personal blogs and vlogs from expats, can give you a really unique window into your chosen destination.
Respect Local Customs
Study up on what's appropriate in terms of behavior and clothing. Visiting holy sites without wearing the proper attire and exhibiting appropriate behavior, can be extremely difficult. Knowledge of local customs will make you more at ease. It's also much less disruptive to the locals.
Queue jumping is acceptable in some countries and unacceptable in others. A little research on your part, can go a long way in easing the frustrations of waiting in line.
Respect the environment around you, as more often than not, resources are scarce in developing countries, and may not be what you are expecting. Don't exhaust local supplies by overusing water or leaving excessive amounts of garbage in your wake. Locals will only be annoyed by what will be perceived as selfish behavior on your part.
Always bargain politely. Haggling over prices is seen as a fun type of "sport" in many foreign marketplaces and shops. It is even expected in others. Don't take your dickering too far though. In developing nations, a dollar or two will usually mean far more to the seller, than it ever will to you.
Tipping can be expected in some places, while seen as an insult in other locales. Check beforehand to find out whether tipping is desired or expected. If tipping is required or encouraged, ask a guide for the typical amounts to give.
Watch Your Hand Gestures
As insignificant as they may seem, one needs to use caution when gesturing with hands. When it comes to body language, err on the side of caution. Avoid gesturing with your hands and even pointing, if you're not sure what you are silently conveying.
Remember, you are representing the country that you are from. Don't spoil a place for other visitors and tourists from your home country, by exhibiting any ignorance of acceptable behavior when abroad.
Etiquette Enthusiast, Maura J Graber, is the Site Editor for the Etiquipedia© Etiquette Encyclopedia