Miles, nice to see you keep working hard man...
First of all, your values keep improving, at least for me, and they are looking pretty solid man
I know you like crits like me, so, I think the last portrait, seems pretty bad
when it comes to proportions, just as Lyno said, and actually her head
seems really off from her body, like, if they aren't united, dunno how to explain it, seems pretty unnatural, other than that, it looks really good
If you have time visit my sketchbook and tell me what you think =)
keep it up