Etiquette in Thailand

Thai people prefer to build personal relationships before discussing business.
Initial meetings will always take place over lunch or drinks and entertainment

is part of developing business relationships. Thai people generally value enjoyment
(kwam sanuk).

Body language is important in Thai communication and respect and politeness
should always be shown. Being receptive to subtle body language and indirect replies
will help to avoid confusion and misunderstandings.

           
Appointments for meetings should be made well in advance. It is a good idea to
confirm the details of the meeting the day before the arranged day. By arriving
on time, you are showing respect and foreigners and Thai people are all expected
to arrive on time.

           
A business card should be offered with the right hand. Take time to read the card
and make a polite comment about it.

        
Dress code in Thailand Appearance is very important to Thai people. Business dress
code in Thailand is conservative. Men should wear suits and shirts. Women should
wear plain dresses or suits. If skirts are worn, they should be knee-length or longer.
The shoulders should always be covered. Smart shoes, and socks without holes are
essential in case whereby shoes are to be removed. Do not wear black for all uniform
as this is only worn to funerals.

On casual occasions men should wear slacks and shirts and women skirts and blouses.
Jeans are usually also worn by both men and women.

Source: Business Etiquette: what to consider when doing business in Thailand