Nice studies, nice values, nice sense of humour and nice moon fetish. There's good character in your faces too.
Not sure what you were going for with that last lanscape, I think it looks a little boring atm, I guess just padding out your first post aye? ;P
I like your muscle and facial sketches. The linework and sense of mass is pretty good. (Also that landscape does not need giant snow women. Maybe it's not the most polished piece, but I thought there was a nice subtle sense of distance in the sky. Solid.)
I'm really impressed by your sketchbook. I put myself in the position - when I was first sitting down to digital painting - where I was essentially hamstringing myself, in an attempt to make it look more traditional. I still haven't mastered any particular aspect of the digital process, but I sure do love ctrl + z!
Looks great so far, man. I know you wanted crits, but it's a sketchbook and I really find the material to be incredibly appealing.