I'm not a portrait photographer by any means, but this needs more light imo. Her face and shoulder are lit, but there is no detail in her hair or dress, and her right arm looks much darker than her left. If working with one light, a homemade reflector (white foamcore or cardboard with aluminum foil) could be used to illuminate the unlit side.
Pretty girl, nice studio setup, but the light is off quite a bit. In full body shots you need to make sure that the light is even across the entire body not just the face.
Also shooting a black dress is difficult, so you will need to make sure you had more lights