I'm a beginner and I apologize profusely for this fact, but it's sad is what it is that you've received no replies so I'll give this a whirl.
You're good. Alot of people are bad but your good. Or at least you come off as good. The issue, as I see it, is that you've constrained everything to the standard standing poses and mug shots. All the art you posted (except for the last two) is of interesting guys... doing nothing. There's the one picture of the guy with the foreshortened hand, but even that is standard and canned, with the hand going directly forward and everything else flat. Loosen it up man. Play with some perspective and angles. There is the fightclub guy but it's a ref and even with that fact really not all that natural looking. Make them look like people instead of props.
Aside from that, uh... shade with a greater range of values. (I think someone already told you that on one of your other threads and they were right to do so.) Anyway that's my input. Hopefully a pro will crit you and then you'll feel all kinds of cool. Whatever happens keep up the good work man.