It isn’t nearly so difficult to listen to a recital of your faults if the person criticizing begins by humbly admitting that he, too, is far from impeccable. Admitting one’s own mistakes – even when one hasn’t corrected them – can help convince somebody to change his behavior. Try using phrases similar to these: You are better than I was at your age. I have been guilty of so many stupid, silly things myself; I have very little inclination to criticize you or anyone. But don’t you think it would have been wiser if you had done so and so?
*Compilation taken from “How to Win Friends and Influence People,” by Dale Carnegie