The New York Magazine has an interesting article about
The Power (and Peril) of Praising Your Kids.
In essence, it recommends not to just say to your son or daughter "You're smart!" or "You're great!", but to be more specific and praise their efforts like "You have worked really hard!" or "You really tried to be a good team player!". Studies showed that children that have been praised unspecifically tend to think their talents are given (by genes, by nature, by birth) and they cannot do anything about it. Thus, if challenged with problems they are not good at, they prematurely give up on them instead of trying harder.
One of the statements I liked the most in the article is
“What happens to your brain, when it gets to think about something hard?”
“It gets bigger, like a muscle.”