Here's a useful tip for those still learning the arts of Photoshop.
A Common colour change is to black, with this is a common misconception that black is black.
Well, actually in photos it is more common that black is more of a dark shade of blue.
Here is what i mean.
Original pic ...
Then Desaturated... Still pretty normal.
Okay after adjusting for contrast i've made it Black.
Looks okay, but doesnt really look real.
So here it is with a hint of blue in.
All i did was saturate it in blue, then turn down the saturation until i was happy.