Hi,
I have lived and work in Bangkok for 10 years. Just bought a condo in Cha-am as a weekend getaway, I have gained much more useful Thai culture information from my experience so just wanted to share about Thai business customs to all on this forum.
In business circles, some Thai people will have a reasonable command of English. However, most Thais do not feel comfortable speaking English. Address a Thai man or woman by their first name, not their surname, using the prefix Khun instead of Mr or Mrs. It is not considered informal or familiar to call Thais by their first name. Although Thai people appreciate punctuality when conducting business, there is a different concept of time in Thailand. Deadlines are often overlooked and it is necessary to allow for this when scheduling meetings. Don't contradict or criticize people in public. An essential tool for success in Thailand is patience. A person who lets inconveniences pass and forgives easily is respected.
Have a good day!
Steve W.