While Thailand is superficially becoming more and more Western, the Thai culture and habits are still practiced widely by its people. Foreign travelers may find it difficult to navigate the many cultural norms of Thai culture, but you don’t have to worry.
Thais are generally tolerant of well-intentioned faux pas, and they do appreciate earnest attempts by foreign visitors to pay respect to Thai culture. Here’s a short list of do’s and don’ts that will serve you well on your next trip to Thailand.
Smile. In fact, smile as much as you can. Thais smile under any kind of situation, a cultural habit that Westerners often can’t understand. It's related to the Thai live-and-let-live, take-it-easy culture - something best expressed in the common Thai turn of phrase "mai pen rai" (never mind). So "mai pen rai" - when in Bangkok, do as the locals do.
Related to the first point – for Thais, only fools and people of poor upbringing lose their temper in public. Loud voices and angry talk can be extremely counterproductive in Thailand. Thais value keeping “face”, for themselves and each other. Smiling (see above) will get you much further than a raised voice.
Remember the sacred and taboo parts of your body: head and feet. For Thais, the head is the most sacred part of the body, while the feet are the lowest and the filthiest. (A cultural trait Thais share with the Balinese, Khmer and the Myanma.) Don’t ever touch a Thai person’s head; at the same time, you must never show the soles of your feet to anyone, or use your feet to point to something.
No shoes allowed indoors. Before entering a house or office, it’s polite to leave your shoes outside.
The science is on the Thais' side: a study conducted at the University of Arizona found that an average of 421,000 units of bacteria live on the soles and outsides of shoes… bacteria that can be tracked onto clean floors if the shoes are kept on inside the house.
The bacteria probably comes from “frequent contact with fecal material, which most likely originates from floors in public restrooms or contact with animal fecal material outdoors," said microbiologist Dr. Charles Gerba. "Bacteria can be tracked by shoes over a long distance into your home or personal space after the shoes were contaminated with bacteria."
Skip the P.D.A. Public displays of affection are not encouraged in Thailand.
Practice the wai. Instead of shaking hands, Thais “wai” to greet people. The “wai” is a short bow done with hands held fingertips-together close to your chest or face. A proper “wai” is not as easy as you’d think, so practice a little to get the hang of it. Never “wai” someone of lower status – even it sounds like the egalitarian thing to do, you’ll only embarrass the person you’re “wai”ing.
Be culturally sensitive. Buddhism is practiced by most Thais, so one must take extra-special care not to offend their religious sensibilities. Wear appropriate dress before entering a temple – avoid sleeveless shirts, flip-flops, and too-short shorts or skirts, for starters. Leave your shoes outside the temple as you enter.
Show respect for the King and his family. Thais will not appreciate even the friendliest jest about their monarch. Thai people have a deep respect for their King, an affection that reciprocates his many accomplishments and sacrifices for the country. Remember, respect for the King isn’t just polite, it’s the law: you can read more in this article on Thailand’s Lese Majeste Laws.