I think the more you study proportions the easier it will come to you. One thing to keep in mind is how everything related to everything else. I know I have a big problem with keeping everything relative. Not to say you have that problem, but something to keep in mind. How long did you do each pose? I've been doing 1 min gestures, and I seem to have a problem with doing detail before getting the overall shape and feel of the gesture. I really have to scribble of I will get to focused on the smaller detail. have you have a similar problem before?