“What I like about your (idea, work, behavior) is …. What would make me like it even more is ….”

when to say it: When you’re dealing with a particularly sensitive employee and you want to keep the interaction positive so they don’t get defensive.
how to say it: Give meaningful, specific examples of what you like, and explain why you like these points. Then deliver the followup (“What would make me like it even more ….”), which will encourage better work.

Source: Caroline Webb, author of How to Have a Good Day: Harness the Power of Behavioral Science to Transform Your Working Life