For over a year now, I've been reading and researching everything I can get my hands on about customers. One of the best books I've read to date is only 11 pages long, and it's free. The book is called "The Six Laws of Customer Experience". I highly recommend that you download this book and apply as much of it to your business as you can.
The author is Bruce Temkin, vice president & principal analyst with Forrester Research. You may want to follow his blog as well. I do.
