The king and Royal Family are highly revered. Negative or disrespectful remarks about the Monarchy are considered offensive and in some cases punishable by law. To Thais, the head is sacred, the feet base. Therefore, it is impolite to touch the head even head a friendly gesture. Likewise, do not point or gesture with your feet and avoid stepping over or across people or things.
Always dress appropriately at all religious sites: shorts or revealing clothes like sleeveless shirts are not permitted.
Thais greet each other with a prayer like gesture called a wai. The wai has far more social significance than a western handshake and in general, the younger person or the person with a junior ranking first offers a wai to an elder or senior, who returns the gesture.
Expressions of anger are regarded as crude Not a tradition Thai custom though gaining wider ages but often the coins in changes. Texi fares rounded to the next 5or 10 bath are normal. Restaurants and hotels, which change 10%, require no additional tip and it is all right to keep the change.