1. The customer is always right—provided the customer is right for you. Deciding which customers you engage with and what you are willing to do for them is a powerful exercise in defining your brand.

2. Don’t surprise and delight your customers— just delight them. A well-designed service is predictably excellent. You delight your customers by meeting their needs within the expectations they have for whatever you are offering, whether those expectations are high or low.

3. Great service must not require heroic efforts on the part of the provider or the customer. Delighting your customers should be efficient, effective, scalable, and if not error-proof, error-resistant. That is what makes it reliable—the delightful non-surprise of the Second Principle.

4. Service design must deliver a coherent experience across all channels and touchpoints. Simply put, any place you choose to play, you have to play well. And anything you are going to do, you have to do well in every way.

5. You’re never done: Anticipate, create, innovate, iterate—and repeat as needed. The rules for innovation in services aren’t the same as the rules for products; companies need to learn service-innovation best practices and harness the power of the new. Looking through the lens of service design, and bearing these principles in mind, it is easy to see how whole industries could be enormously improved by better service design and delivery

Great Resource: Woo, Wow, and Win by Thomas A. Stewart and Patricia O’Connell. Customer is right always.