Nice, I love how the head pops from that red.My only two crits would be that the hands at this moment get lost(but that just might be that you haven't gotten around to them yet) and the cars in the back at the moment don't look as believable as the rest of the picture.I really like what you are doing with the buildings in the back.P.S good luck at Comic Con, let us know how it goes!
the areas I would spend more time resolving are: her ear, that mesh on her right arm, the cars, whatever tools are on her utility belt, and what appears to be a wisp of smoke coming from her left wrist. Looking damn good so far!
Love the postapocalyptic feel =D I would say work on the belt/utility belt/stuff on the belt, the hands and foreshortening of the gun .. it gets kinda confusing and muddled especially in the hands area. I'm not sure if it's your intention but her hands are really red.have fun/good luck at comic con!