The method here was one I had researched as a more efficient way of getting better at painting and at working more cleanly in Photoshop. I have utilized several layers, broken down by main colors, and painted at 100% opacity for most of the time while having the layer set to Multiply. This way the colors and the undersketch's grayscale shading both show and mix together in an acceptable way. Of course, beyond that, there were small tweaks as needed.
As always, happy to hear feedback and hope you all at least enjoy!
Stay tuned as there is more to come!
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