Hello Tess Wilber,
I am sure you probably already saw these; but, here are some links for you to check out:
A google search shows many pictures, also. The trick is to work not only the joint but also the joint on either side: hip and ankle, making sure to work all surrounding muscles to stay in balance. Musculoskeletal balance is the other key. Don’t underestimate flexibility, either; a flexible muscle is a strong muscle.
Natalie aka NAPS 2 B Fit.