Looks like Radium is my critic replacement for you, Spam, 'cause I was gonna say the same thing. Most artists use shapes so that they know WHERE to put all the body parts, (it's also used for proportion, but I don't think that applies here).

If Spring wasn't the one who suggested you use shapes, then I strongly suggest you go knock on her head and make her show you, 'cause I see her use'em all the time. Very well, I might add, but that goes without saying. (I don't actually use shapes myself, so I wouldn't be the one to ask).

-Bluezy Bunny