Begin with praise and honest appreciation. Call attention to people's mistakes indirectly. Talk about your own mistakes before criticizing the other person. Ask questions instead of giving direct orders. Make the fault easy to correct. Make the other person happy about doing what you suggest.
Dale CarnegieIf you want enemies, excel your friends; but if you want friends, let your friends excel you.
Dale CarnegieIt isn't what you have, or who you are, or where you are, or what you are doing that makes you happy or unhappy. It is what you think about.
Dale Carnegie