Hey! Great start, I'm looking forward to seeing more studies. Maybe you could say what you were focusing on studying in each or groups of studies. There's plenty of different approaches to painting subject matter/ drawing and perhaps if you were to state what your approach was each time we'd be of more use to you in our critiques. That way we could analyze harder and ask better questions as we become more knowledgeable with your weaknesses and strengths.
My biggest crit and perhaps the one that may help you the most is that you should stay away from a very dark outer contour line in relation to the inner contour lines. In other words, your values are very blown out. I think if you "lost some edges" it could help significantly and help you to see things more structurally than graphically. Also, the rate of turn on most of your forms aren't gradual enough. I know this because it makes your values look "blown out". Someone you can look at is Sargent's charcoal drawings if you'd want to study how to use edges and how to turn the form efficiently. In order to get that global turn that Sargent was so aware of, it will take a lot of practice. Someone else I suggest looking at is Ryan Wurmser and Ted Seth Jacobs. These guys know how to turn the form magnificently in a structural manner. Here's a link to Ryan Wurmser's figure drawings.
http://ryanwurmseratelier.blogspot.com/2...-2010.html . Looking forward to more studies!