I'll be honest here, its a bit hard for me to critique your work. Most of them look really expressive and surreal with fine art implement into it, which is something to truly respect.
The only thing I can really say is try to bring your piece to a more complete stage? As in take a little more time to work on them and truly push it by blending shades in the appropriate areas and try to work out the lighting a bit better.
I notice you usually dont pay much attention to the hands and feet, maybe thats something to work on?