Compliments and criticism are the two edges of the feedback sword. Today, The Chief Happiness Officer’s Blog explains that to be effective, compliments must be specific. This generalizes well to ‘feedback must be specific’. In particular, you want to clearly describe the behavior that you observed. For instance: “Bob, I see that while you were fixing that bug you also added several new tests and refactored the module.” Now that Bob knows exactly what you are going to compliment him on, tell him about the impact this will have: “That will really make it easier for people to work in that module in the future, and probably prevent some bugs too!” At this point, if we were delivering criticism, we would request a change in behavior. Since we are giving a compliment, we can simply say thank you: “I really appreciate you doing that. Thanks.”

You can find more on feedback here.