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 CarnegieDo you know someone you would like to change and regulate and improve? Good! That is fine. I am all in favor of it, But why not begin on yourself? From a purely selfish standpoint, that is a lot more profitable than trying to improve others - yes, and a lot less dangerous.
Dale Carnegie