Temple and cultural etiquette
Thailand is predominantly Theravada Buddhist and reveres the monarchy; both deserve respect. At temples, cover shoulders and knees, remove shoes before entering buildings, and never point your feet at a Buddha image or person — feet are considered the lowest, dirtiest part of the body, the head the most sacred (don't touch people's heads). Women should never touch a monk or hand things directly to one. The standard greeting is the wai (palms pressed together with a slight bow). Public anger or loud confrontation causes loss of face and rarely helps; calm and a smile go far. Speaking disrespectfully of the King or royal family is a serious criminal offence (lese-majeste). Dress modestly away from the beach.
General information, not legal advice. Laws and practice change; for a decision that matters, confirm with the authority named in the sources or a licensed professional.