Ummm, dare I say, "Hot!"? I like this series very much, but I think it would benefit from a little more fill light image left, and in 2, 3, & 4 the lighting on your face is a little over-bright. That aside, nice work.
I'll go one light further..... light your background or yourself by having a light fire at you but behind you. This should help separate you from the background. You seem to melt / get lost into the background too much.