Service Innovation
I remember feeling there was some mystery to innovation for services until I read a paper by Gabriel Bitran. After the paper I remembered that the main thing to focus on with service innovation is the same thing one should focus on with product innovation. As always with innovation, the thing to focus on is solving a customer problem.
There were some other interesting things in the paper around a dominant design that emerges for services, but that happens for products as they mature too. If you had to design a mature service like a hair salon, you wouldn't want to innovate where it wasn't needed because it would confuse the customer without adding unique value. Imagine walking into a salon and being told they cut the left sides and right sides on alternatiting days of the week. Unless that somehow addressed a novel value proposition, it would just be something "creative" that wouldn't solve a customer problem.
Focus, focus, focus on solving problems for customers. I don't think we can repeat that to ourselves enough.