Deviation Actions
Perfect example of an image needing better lighting! (which I mentioned in my other comment). The composition of your model is actually BETTER than the original photograph, so well done, there! However, it doesn't match the window frame, whch has no highlights at all. The major soucce of light for the model appears to be coming from the top-right, so you want to highlight the cross pieces of the window frame on the top and right edges, especially making a fluid transition at the intersections. The highlights could dim a bit as you get further down the window frame, maybe even scattering them to give a more rugged appearance or..?
Anyway, This image grabbed my eye as a perfect example. The model shows that you can do the lighting and shading right, but the window shows where you could do better. :)