Aircraft Command Gaining Leadership Skills to Fly the Left Seat by Sal J. Fallucco. 2008 reprint paperback edition published by Ashgate. ISBN is 0754618358.
I can only recommend this book. If you want to prepare for your command all this book can tell is how you should be Knowledge within the rules and regulations. And the fact that you it is all your responsibly to manage every flight ! Not only fly the plane but manage it