Half drawing

I am trying out the symmetry tool again. I used this one before once i think and i wanted to do a portrait. Even though this tool is amazing but when doing portraits, i probably shouldn't use this because no one's face is this symmetrical.

I first use black and white color to shade the portrait because that looks quite good. But i don't know how to apply color after. So when i used an overlay layer to apply some color it looked a bit weird. As you can see because thats what i uploaded.
Anyway this is not a final piece i am gonna keep working on it until i make look a little better.