Good Services is a straightforward, to-the-point guide to designing services to provide the best outcomes for their users. The book is structured around 15 principles for service design; the author, Lou Downe, developed the principles in practice as the pioneer of service design in the UK government. This approach led UK.gov to be the standard of excellence by which all government services websites are measured.
Bonus: the book is very well designed. I read mostly on a Kindle these days, so it’s nice to spend some time with a really solid piece of paper and ink.