Always give people the opportunity to do things themselves, never tell someone, let them do it, let them learn from their mistakes. A technique like that makes it easy for a person to correct errors. A technique like that saves a person's pride and gives him or her a feeling of importance. It encourages cooperation instead of rebellion. Resentment caused by a brash order may last a long time - even if the order was given to correct an obviously bad situation. Asking questions not only makes an order more palatable; it often stimulates the creativity of the persons whom you ask. People are more likely to accept an order if they have had a part in the decision that caused the order to be issued.
*Compilation taken from "How to Win Friends and Influence People," by Dale Carnegie