"Wow, that's a really good score. You must be smart at this." We praised the children in another group for their effort: "Wow, that's a really good score. You must have worked really hard." That's all we did, but the results were dramatic.
This goes back to Golden Child Syndrome, if you praise the child about themselves, they can become self-obsessed and not do as well, just like the article says. But if you praise the child on how hard they worked, or tried, etc., then they tend to do better.