I have a copy of this book and have used it as a great reference for best practices since before the days of Tableau. I definitely recommend this book as a reference to have on hand especially in the early days of developing dashboards. This book will explain how to keep your visualizations simple, effective and how to use colors effectively among other things. There are some other great books by Stephen Few and many others but what might be more helpful is the latest book that Tableau was involved in The Big Book of Dashboards: Visualizing Your Data Using Real-World Business Scenarios by Steve Wexler which gives case examples and possible templates for many different business situations. If you have time to search check Gallery | Tableau Public as most of the Vizzes are available for download and you can reverse engineer them to find effective formats suit your own needs if you find something that looks appealing. This is one of the best ways to learn in my opinion.
I hope this helps!