I actually think its a good effect only colouring key aspects to your pictures in the comics. I would say along with the character you should have coloured the dumpster, door and balcony.
It reminds me of movie Sin City which I believe was based on a comic where the movie was a black and white with only certain things being in colour. It gave it a dark yet dirty look which I think would suit this story quite well, and if you go with that style it doesn't matter that your colouring skills aren't top notch yet.