More courteous is the comparative and Most courteous is the superlative
Please Thank you Please may I have Thank you very much Would you like It is nice to meet you
As nice as ninepence
I am a courteous person, but I don't think society as a whole are very courteous at all, Courteous goes beyond Thank you, or yes mam, How many people help an older person put there groceries in there...
Polite, well manered, proper behavior.