In animation it's fundamental to be consistent in the structure and volume to avoid deformations and movement mistakes.
Control volume and structure according to the perspective, camera angle and action
Very important point
When you draw, you must create virtual lines of perspective according to the position of every parts of the character.
Those lines don't have to be drawn, with experience, this construction will be only in your mind... But you must give the habit to your eyes to see in 3 dimensions and understand the volumes in every direction.
Practice the construction, volume and perspective of the body with life drawing sessions or directly from photos. Try to understand the volume, even for the hidden parts.
Design by Otto Schmidt
It's a good exercise to use photos or videos references to practice volume and construction.
In slow motion
This video is also in the animation page, but the approach of Toniko Pantoja for the first rough is very interesting for our construction topic here.