These days, I color my images very straightforwardly.
I always begin all of my images with backgrounds by painting out simple grayscale lighting — paint simple shadows to get a feel for light direction and how cast shadows will affect the scene’s composition. I will sometimes go through 3 to 5 repaints of the shadows until I find a direction that has maximum impact. Once found, I begin filling flats to serve as undercolor for the painting to come.
I do tend to separate the objects in my scene according to depth, (line art on top, then foreground color, characters, middle ground, background, sky, etc) which leaves me with about 5 layers on any given piece by the time I’m done with it. While I’m working on it though, I often have layers floating above each major element, where I can color detail and merge down once I’ve reached a satisfactory level of finish. (I paint in all of my scene’s shadows on these layers, for example, then merge them down when they’re finished.) All of these layers are always set to “Normal” blending. I rarely ever use multiply/overlay/dodge blending modes to achieve effects anymore, (maybe just to fill in a cast shadow here or there, but they get merged right after anyway,) I’ve learned some time ago to do as much as I can with pure color as possible — you get far more control in the end, and you actually work FASTER since special layers can block up your progress prematurely.
I rarely use the color sliders. I have a massive custom swatch library that I pick colors from and do on-canvas mixing. I find this not only a little easier than twiddling little sliders around, but it’s more fun to me, too. Check it out:
Elsewhere I pretty much just use a round brush 99% of the time. I take Feng Zhu’s advice and, especially early on, try to avoid using brushes with opacity change based on pen pressure — as that’s not realistic to how paint actually performs from a brush. I do tend to use brushes like that later on when smoothing things out, though. But it’s just not necessary earlier on.
Lastly, when I’m done with coloring/painting a picture, I WILL put a layer on top for post-process effects — things like light glows, or an adjustment layer to fine-tune contrast or whatever.
And that’s pretty much it!