Here's something that I think would go a LONG way in creating more customer delight and directly influencing word of mouth factor.
Do something memorable each day for one customer. It could be something like an invitation to dinner, a custom gift, or an unexpected and substantial discount.
But don't forget the most important part.
The context.
Share why you're giving this gift or sharing this gesture. It must be a genuine congratulations, thank you, or you're awesome.
The key is genuine.
Do this every day for a year or every week, depending on how many customers you have.
I know you'll only get positive results.