Children need and deserve realistic feedback about their accomplishments to understand their strengths and weaknesses. If you gush over everything, they will never recognize that some areas really do need improvement. I can't wait to hang up this painting. Think of praise as a form of feedback. The more specific you are, the more important information you impart to the child.
Every child has some area of competence, one that can serve as a source of pride and accomplishment.
Encourage that special talent and the child's pride in his achievement will transfer to other work. Too often, adults reward the results and forget about the effort. Look back two or three months on the child's progress and concentrate your praise on how much a child has improved. Many times adults compare one child to another. Encourage children to participate and do well because they enjoy something, not because they want to beat out someone else or prove they're smarter than someone else.