Sa-wat-dee kraup (male speaker)
Sa-wat-dee Kah (female speaker)
Note: Sawatdee is the greeting. Kraup (male) and Kah(female) are polite endings. You want to include them especially in any formal settings. It like when we add 'please' to a question, except they add them to questions and statements.
As the poster mentioned, Sabai dee mai means how are you. However, Thai speakers don't ask this question unless they're familiar with the person. Otherwise it's considered an odd question. If you do know someone and want to ask, again add the polite ending. Sabai-dee mai Kraup?
Thank you is - Kop Khun Kraup (or Kah for a woman).
P.S. Good idea learning the greeting in Thai. They really appreciate it when we make that effort. Especially considering so many of them spend so much time learning our language.
Thai language student and part time resident of Thailand.