Don’t emphasize the mistakes. Do the opposite. Praise the things the person does right and minimize the errors. Tell your child, your spouse, or your employee that he or she is stupid or dumb at a certain thing, has no gift for it, and is doing it all wrong, and you have destroyed almost every incentive to try to improve. But use the opposite technique – be liberal with your 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 the window in order to excel.
*Compilation taken from “How to Win Friends and Influence People,” by Dale Carnegie