Your sketch book has a lot of interesting stuff even in te first part, where as you put it you didn't cared to develop anithing, I think that there the drawing is very spontaneous and that you have found some good ideas there.
In the #50 post I've noticed that you have some problem with anatomy but not with the gesture drawing so a little bit of study of anatomy like you are alredy doing and you will be fine
*Rena* : thanks, Yes I guess I was coming up with a lot of random ideas back then! And I sure need more practice on anatomy, how muscles are connected to eachother and proportion.. I've been doing a lot in my sketchbook lately but will upload it when I get the chance again!
ConnyNordlund: I guess Marko looks like Al! but uhm who Marko?
One of the first things I noticed was how much black you used in your studies.
way too much! don't just do light&dark. Try to use like 20 value for dark areas and blend it out properly to some mid-range value and blend that out to like a 80. You can always add contrast later but adding mid-range values does not really work.