I recently put up my first studios in the portrait forum. I got lots of great comments which helped my next attempts come out much better.
From that experience, things I'd say are:
1. The WB is off
2. You should have a strong key light off to the side, and then your fill light should be next to the camera and relatively weak.
3. You need a reflector below to stop the shadow on your neck.
4. f/2.5 is too open, and I'm not sure what lens you are using, but it looks very soft. Probably want at least f/4.
5. I think there is too much light on the hair. If it was just highlighted, it would give the photo a more 3D look.
It is amazing how much good a head tilt does on a portrait!
Steve W weather photos: http://home.comcast.net/~scwest/atmo/