Hey there! So cool portrait! :D And well... I do not have experience painting with colour pencils, but I could say that yes, if you want to introduce darker values in the portrait, you'll have to blend the colours gradually. To create a soft transition between your light and dark tones. Your dark can be the opposite colour of your light or local colour, in this case, some blues. This is how I've seen how other artists do it, tho. Hope this helps! :)











