it looks good. If you want greys with b/w tho i would suggest actually doing it, instead of a saturation mod, which it seems this is. The sat mod will wash the image away, too much, so you've lost a lil clarity in the image, definition. If you can do what it appears you've done then you should think about using PS or another program to create your elements. You could do a bitchin black scheme, which grey and white highlights. Your skulls could be in color and you could even animate them with fire for instance. Keep going with it, the hard part is done.