Give them the example...think of what you've done that made the client extremely happy and maybe complimentary. I personally had some of my delivered experiences as a bartender and server written up in complimentary ways on TripAdvisor, Metromix, etc..., so I pointed them out and the circumstances that brought the compliment about...but beware, be prepared to prove it if you have the write-ups...they just may look you up, they ARE public domains, so don't B.S...