The Secret of Socrates

How to Win People to Your Way of Thinking

In talking with people, don't begin by discussing the things on which you differ. Begin by emphasizing – and keep on emphasizing – the things on which you agree. Keep emphasizing, if possible, that you are both striving for the same end and that your only difference is one of method and not of purpose.

Get the other person saying "Yes, yes" at the outset. Keep your opponent, if possible, from saying "No". A "No" response [...] is a most difficult handicap to overcome. When you have said "No", all your pride of personality demands that you remain consistent with yourself. You may later feel that the "No" was ill-advised; nevertheless, there is your precious pride to consider! Once having said a thing, you feel you must stick to it. Hence it is of the very greatest importance that a person be started in the affirmative direction.

Reference:  How to Win Friends and Influence People by Dale Carnegie