Having some issues with my new PC and a tablet, so no redlines for now.
RavingRabbid: The skeleton doesn't make much sense to me. Not only the lack of limbs, but his inner boddy is a pear-shape, without mich dimension to it, and has strange half-circles on it. I don't see what you're trying to draw there. Try sticking to simple blocks (squares, circles, etc) to make the basic skeleton as simple as possible.
Krahhl: Much more like it. Keep in mind though; the circles you use for the hip and shoulder are basically the attachment points for the legs and arms. If those don't take up the full width of the creature, try and show the viewer how the muscle extends into the body.
SunnyGreens: Chest could do with a bith more definition, but great work nonetheless.
Krava: I'll admit, that thing's funny to look at. I think one of the main issues is that the body itself is a bit too thin; use the circles for the attachment points to define the size you need. Most creatures - particularly humanoids - are widest at the hips and shoulders, to it could taper off a bit in between. Do note that that 'widest'only goes for muscles and bones; plenty of fatties who'd disprove it otherwise :p
xBerzerk: You're free to join up, as is anyone else! The next lesson will hopefully start either today or tomorrow, so that should help, too