First, let's start with what you shouldn't tell your kid after he or she does something well: "I'm proud of you."
So, was that surprising? It was the first time I heard it. The problem with it, according to Hal, is that it is really about you. Should they do things just to please you? While it may be nice to think that way, the answer is No. They should do things to please themselves, because it is the right thing to do.
Let's turn the question a different direction - should they do things to please people? No. I don't want my kids trying to do things to please their friends, or just to please a boss. I want them to do it because it is the right thing to do, which may go against the grain and the crowd.
Let's turn it again - what happens when they don't do something that great? What happens when they strike out at the plate (and when they got a hit you said you were proud of them)? Are you now not proud of them? I hope not. I don't think too highly of those kind of parents. But if you only tell them you are proud of them when they do the great stuff, the implicit message is that you are not when they fail. I want my kids to fail, because at least it means they are trying, they are risking.
The last turn - what if, instead, you ask if they are proud of themselves? Help them to think through their accomplishments, especially their role in being responsible and taking steps.
If you want to praise your kids, the book The Narcissism Epidemic (83) says to praise your kids for working hard, because then they will want to work hard. Don't praise your kids for being smart - if it comes to a situation that calls for hard work or one that confuses them, they will shy away from it to protect the "smart" label. In these studies working with kids and how words affect them, those that were told they were "smart" struggled when they got to a problem which was difficult for them; the label "smart" scared them more than helped them. Those that were told they were hard workers buckled down because they believed they could figure it out.
Words matter. Be a hard working parent when it comes to your kids.