Hey, first up: sorry about the rushed drawings but I'm short on time and worried I might forget about this later. So here's a quickie from left to right:
Basically I think you've actually got the proportions and the gesture done well for your sprite. To make it better, you'll need to get the 3D form of it to show through your lineart as well as your coloring/shading.
The first image on the left is a rough idea of what I mean: the human body is composed of cylinders, which has curvature and form in it. It's easiest to see this when you tie a rubber band to your arm or wear banded socks, and you can see how it molds to the form of a body. A U curve is a downward pointing cylinder, and an n curve is an upward pointing cylinder.
Once you understand what the form of the person is, you can then apply overlapping lines to it to show what is in front and behind even in a subtle part of the person. The first red flour bag for example, would tell a different message if it was upside down, based solely on the overlapping lines in the middle.
Put this all together, and you get a more 'informative' line art where you can tell what the object's form is like through lines alone.
Finally, and this is a minor niggle: your sprite's a bit off balance, with its center of gravity slanted off to a side. To compensate for the tilt of the upper torso, you'll need the pelvis to move in the opposing direction. Without changing the pelvis, you can get it to be a bit more balanced if you rotate your entire sprite to be straighter. Getting it to look balanced while slanted, is a whole other barrel of fish, which brings me to this:
Proko:
Who talked about the bean bag
and his Robo Bean.
If you have time, crunching through his videos will help (Plus he explains it a thousand times better than me). I know it might seem completely different from anime or a style you want to achieve, but these are the foundations and they're great to know regardless of stylistic choices.
