I think you've really gotten the general forms well, the only improvements would really come with time and practice. I'd just say maybe not FILL the drawings? As in, if I'm assuming correctly, the sketches are for capturing form, so for that, you don't really need to fill/color the sketches in any way. Focus on quantity and timed works rather than a full work of art. That yields results the quickest.
1
1
1
