Alright lets dig right in shall we? I first want to start of by saying you have a lot of things going for yourself in this portrait. composition, > light source, varying values and much more. Rejoice! you've got the hard parts down, now all you have to do is let the elements you've set in place work for you. ("work for me....well what does that mean?" ) Example you see that nice steel pauldron she's wearing on her shoulder, you've done a smashing job contrasting it with a dark soft undergarment! However this is where we want to take it up a level. The light source you created in this piece should really accentuate that pauldron or "Shoulder guard" making it an entirely different tone than her breast plate, though this would still be very subtle! I'd also recommend for the sake of the full utilization of this piece that the light source be a lot sharper in order to create some nice contrasting tones in the hair as well. To some this big saga up, Play to your pieces strengths, Darker shadows, Lighter Highlights to pop her out that grey back round but most important of all, HAVE FUN!