If you're in a position to review employees, never ever ever let them go into a review not knowing what is going to be on it. How do you do that? Communicate.

If you're in a position to review employees, never ever ever let them go into a review not knowing what is going to be on it. How do you do that? Communicate. Communicate constantly. Talk about their wins. Talk about their non-wins. Talk about their skills. Talk about what needs to be improved. Talk to them about what they want to learn. Talk to them about what they have learned. Talk to them all throughout the year.