I recently read The Principal's Companion by Pam Robbins and Harvey Alvy (2014).
In fact, I used this book as one of the required readings in a graduate class of principals-in-training that I was teaching.
The authors did a very nice job of taking a 360 degree look at the contexts and requirements of the principalship in the 21st century. They addressed the wide array of roles that current school principals must play. The authors provided guidance on using collaboration to collectively craft and deploy a school vision and mission. They discussed strategies to help principals stay focused on the most important thing - LEARNING - while attending to all the other stuff that comes with the job. Ideas for increasing and improving the school-parent-community relationship were provided. Finally, the authors spoke to the difficult challenge of maintaining "balance" between the principal's personal and professional lives.
This book was written as a textbook, but reads in a more relaxed fashion than most textbooks. Glad I read it. And, my students indicated they were glad they read it, too (which is not a common expression).