It is always good to focus on your positive experiences (Campbell, 1957).
If Thais do bring up a complaint with you, such as how polluted parts of Bangkok are, or apologize for how dirty their factory is, it is best not to agree with them directly, but simply state 'It's fine--don't worry about it.'
Be careful not to give too much praise in regards to a Thai's possessions, as he or she may feel embarrassed, or obligated to give you the item in question. It is best to give general praise, such as 'You have a wonderful office.'
Age is also a common question, especially if you are not yet going bald or grey! Direct replies are appreciated, but can be avoided if you don't feel comfortable replying (Campbell, 1957). 'I feel like I'm 21 again!' is a good example of an indirect response.
Be aware that Thais will often state bluntly that you are either fat or fatter than the last time they saw you. Don't take offence at this and simply laugh it off and give a simple reason--usually all the delicious Thai food you have been enjoying recently. There is no need to reply with a similar comment.
The Thai language uses a phonetic alphabet of 44 consonants and 32 vowels (Noochoochai, 1978). All syllables must contain a vowel sound, but may begin and/or end with a consonant sound. A syllable which ends in a vowel sound is called open, and a syllable which ends in a consonant is called closed.