Be punctual. Thais expect a Westerner to be on time, even if they don’t expect it from other Thais, or from themselves.
Express curiosity about Thailand and thing Thai, except for family and living circumstances of your Thai host.
In a meeting, note down mutually agreed matters. Read them back for corroboration at the end. Then, follow up with a written copy. This seemingly plodding method can make matters go much more smoothly later.
Express appreciation for the little things do not overwork ‘Thank you’. A nod or a smile to staff is sufficient. A ‘Thank you’ to the host or business colleague will cover the whole event or experience. Also, don’t interpret it as ‘abrupt’ or ‘short’ when Thais do exactly the thing