One of the first books I dicovered when I began traditional shooting was Archery Anatomy: An Introduction to Techniques for Improved Performance by Ray Axford. Parts of the book are very technical when describing bone structure, force and muscle groups but there are many valuable lessons to be gleaned. I have found the sections on breathing, posture, bow arm, grips and release hand very beneficial. Several sections describe how to establish a routine so your body is working in harmony with the forces of drawing and releasing.
http://www.amazon.com/Archery-Anatomy-Introduction-Techniques-Performance/dp/0285632655