I have tried to post here three times, wrote long posts and managed to close window without posting it. Ha ! So I make a short response in case I manage to close window without responding again.
As for my process I have 2 methods nowadays I use most, but not limited to :
One : idea-> sketch > lineart->flat grayscale (limited to 10% differences- so 10 shades) - > light/shadow grayscale (added 5% variation, making 20 shades) -> gradients > LUT> curves> composite > additional effects/sharpening/curves
Two ; Doodling/idea - > refined sketch - A random depth adding in colour, unlimited palette (absolutely no link to how image colour or theme looks at end) - > LUT - > gradient fill - > maybe additional LUT layer > additional edits based on LUTs chosen - > curves > additional line art > composite > additional fixes> additional effect/curves.
Line art if used is generally a layer between light/shadow and 1st Gradient -LUT FX.
In summary colour in my works are generated via gradient fill+LUT+curves. I rarely manually colour any details at all. But to do that using just those 3 small things, you have to have viable values in depth (light/shadow) layer with right opacity.
I learned this technique from an artist from china years ago, and I love it. It also means I can recolour image in any colour theme, night/day any time I want. It is good non destructive and fast way of working in my eyes.