Hello,
if you are still in “discovery mode” and have a lot of things to learn like me, please have a look to this video (https://www.youtube.com/watch?v=2jX3E3ghSlo)
it is a very smart video from Netaro san, from Love Doll TV, where he is folding the doll with a second screen where we can see the skeleton fold
this is just awesome to understand how to bent your doll without breaking anything, and how to do it without too much effort 
picture speaks more than words
ball joint type
shoulder horizontal
shoulder vertical
waist rotation
waist bent
and much more!