Dress well. Overdress rather than underdress.
Pay great attention to personal hygiene.
Master people’s names. Thais traditionally refer to each other by title and the first name. Mention the last name only in a formal introduction before an audience.
In the opposite of Western practice, introduce a person of lesser status to one of higher.
Smile! As much as you can, smile. Do not misinterpret smiles from a member of the opposite sex.
Pay careful attention to head, body and facial gestures. They are complete signals, not merely amplification of oral expression.
Accept whatever is given to you, especially food or drink. If you do not consume them, you will cause no offence. Just say you’re full, thank you.