Your standing characters slouch comfortably, maybe try focusing on how shoulders sink into the torso and likewise how the torso sinks into the hips, I think this would really help your subjects which are lying down/sitting. Additionally, studies with the limbs broken down into boxes I think would help, let the different faces of the boxes guide how you position the body parts and how they flow into each other.
Figure drawing
Artist's notes:
Trying to make my gestures better, any kind of feedback is welcome. In my opinion I should focus on anatomy more but what's your take on it? Thanks in advance.