I believe there is no greater reference than to offer or if you are the business owner, ask for a client testimonial.
If I am filming a commercial for my client, I ask for her testimonial after we shoot while the equipment is still set up. It doesn't take a script, just a brief prompt by you to ask the client how she felt about the experience and her recommendations to others in that regard.
I know when I hire a professional, I want to treat that pro to a positive referral and I do it in the most creative way I know how - through the use of video and then posting it on as many social media sites as possible.
The following example was simply a service call by a garage door opener company and I took a few minutes to extoll the virtues of the service and put one of the company's techs in the limelight. It didn't cost me much more than a few minutes of shooting and editing and voila!