One of the surest ways of making a friend and influencing the opinion of another is to give consideration to [his or her] opinion, let [him or her] sustain a feeling of importance.
Dale CarnegieThere is one all-important law of human conduct. If we obey that law, we shall almost never get into trouble. In fact, that law, if obeyed, will bring us countless friends and constant happiness. But the very instant we break the law, we shall get into endless trouble. The law is this: Always make the other person feel important.
Dale CarnegieLet us praise even the slightest improvement. That inspires the other person to keep on improving.
Dale CarnegieTell a child, a husband or an employee that he is stupid or dumb at a certain thing, that he has no gift for it, and that he is doing it all wrong and you have destroyed almost every incentive to try to improve. But use the opposite technique, be liberal with encouragement; make the thing seem easy to do, let the other person know that you have faith in his ability to do it, that he has an undeveloped flair for it - and he will practice until the dawn comes in at the window in order to excel.
Dale Carnegie