Wow! Really rare drawings of figures, blossblair, especially the one with your caricature. However, I've got one tiny and insignifigant question: How long did it take to do each and every one of them in your Imgur post link? The case why is because, you didn't label out your time limits. They could've been done in 30 seconds, more and/or less. Hope and importune that you'll give me a totally reasonable answer.
I really like your stylization of proportion and your simplicity of line! You seem to be getting contraposto as well (when the shoulders tilt one way, the hips will tilt the other, in order to keep the balance). I think perhaps you could try some slightly longer poses in addition to your quick gestures, to help yourself notice the bony landmarks of the body. I attached an example file, I hope it helps a little! Keep up the good work!
I really like your scetches to start off! I think my only critiques would be that your proportions are a off in some places, most of the mistakes are that the and chest are short (this may be a style thing, if so, carry on, it doesn't look bad) and the other suggestion is that you should work on hands some more, some of your spacing and shapes are off. Great work though! keep at it!