Fit & Bendy Flexibility Tips: Educate Yourself!
Anyone who wants to train their body intensely should have at least a basic understanding of the musculoskeletal system and kinesiology. There are some really great books out there, two of my favorites are The Manual of Structural Kinesiology by RT Floyd and Dance Anatomy and Kinesiology by Karen Clippinger.
The better you understand how your body works, the better you can design and execute your training plan. The best training plans are customized for your body and your needs.