I returned to working on this portrait today.
I added some darker values. On the clothing, I applied a thin earth green wash, then used a smaller brush to put in more concentrated green accents. I worked these green values into the rest of the figure. I think it needs a bit more work to balance out the values.
I tried to de-saturate the background by using unbleached titanium white and deep naples yellow. And I tried to accentuate the face and skin by mixing naples yellow light with patches of orange, pink and yellow.
My Life In Pencils & Paint 
amazing! This is so energic and colorful, it’s awesome!
wOW! So that’s how it’s done. Portraits are so difficult, but you certainly make them somewhat understandable and attainable. Of course there’s the obvious fact of your talent at sketching, catching the key elements of likeness. I like it very much.