keep up the hard work, someting that really sticks out to me however is how inconsistent your work seems to be? some (well, paintings like this http://www.conceptart.org/forums/att...1&d=1228079766 ) are staggeringly good
whereas ur pencil work is comparatively weak, ur digital painting even moreso. u also have an abundance of sketches but no finished (or even nearly finished) work. i think it would really help you out if u spent much longer on some pieces, exhausting the possibilities of a drawing before moving on. u are starting to develop a sense for light and shadow which is crucial for describing form... dont be afraid to push in some darker darks. i have the same problem...but it can make a world of difference. adding in some pitch black shades can really make shit pop out.
keep workin, ur covering a nice range of mediums etc...its healthy! peace