I liked how the rendering was going in grayscale and then tried to apply colors using some soft and hard light layers in photoshop. Hated it. I seen it being done by Peter Mohrbacher in the below video:
He is an awesome artist but the adjustment layers to apply colors just didn’t work for me. I’ve been doing the caricatures lately with a base color and then staying close to that color in the color wheel. The colors end up harmonizing. That is what has worked for me so far.