Just a heads up for the community that "Using CiviCRM" by Joe Murray and Brian Shaughnessy is Packt Publishing's free book of the day. See https://www.packtpub.com/packt/offers/free-learning.
This book is a good overview of the system despite being written for a much older version of CiviCRM. In particular the early chapter on planning your CRM implementation is still applicable and valuable information that is often overlooked.