Speaking polite is very important in Thai society but you can learn easily for example when you talk with Thai people you should say ค่ะ or คะ( ka ) for women and ครับ( krap ) for man, use to the end of sentence or word such as สวัสดีค่ะ( hello ), ขอบคุณครับ( thank you ), ขอโทษค่ะ( sorry ). Therefore, it will make you look polite more than you say สวัสดี,ขอบคุณ and ขอโทษ