I think the best way to improve twisting is to practice the bean more and more. If you need more on that, watch the anatomy lesson on obliques because it shows you how the stuff in the middle of the pelvis and rib cage work. For tips on simplification I would like to suggest you to take a look at Brian Knox's instagram: https://www.instagram.com/brianknoxart/ He does mannequins so elegantly. I think this one in special it's what you're looking for: https://www.instagram.com/p/CKB4XuJnKj7/ Best Regards