Smooth shading? Probably blending. Have a mid flat colour, pick a shade colour, shade it with a brush with some transparency to it (and preferably using a pressure sensitive stylus). Next choose a colour resulting from that shading and repeat the process. Rinse and repeat ‘till yer happy with the result.

I usually pick a hard egded, square brush with some texture to it, but I also suplement it with a soft airbrush for wider overall shading (usually with an overlay or multiply layer).

Same applies for brightness tho for those I often use overlay or add/screen/ lighten layers. Mess with the layer opacity ‘till ya like the results.

I've tried smooth shading in the past using independent multiply / screen layers, as well as overlay, and an airbrush, but the edges always came out to hard edged, even when using both a soft edge brush and a stylus, with the stylus tip pressure set to control flow... plus the colors didn't look right.

If I'm understanding you correctly, take a midtone, then mix it with a shadow tone until you get a suitable result? Or is this oversimplified?

You have a flat, mid tone colour. Shade a hard block (which ends up looking like cell shading) with some transparency to it. From that result, pick a colour, and shade again (which will result in a light shading), repeat untill yer happy. I actually use hard egded, rectangular brushes for this with some texture. Let me see if I have a tutorial saved regarding that.

(as for flow control, I use a program with different naming, but it must be that yeh, the harder you press, the more opaque is the paint).

As for the colour, depends on what you mean. Do you mean the overall colour pallete or do you not like the colour resulting from the shading?

455 images on my tutorial folder and I didn’t save any about colour blending, go me -_-‘

Anywho, this vid might help. I’m a layer whore but you don’t actually have to have that many. Just in case I shade on a separate layer and only merge if I’m happy with it.

https://m.youtube.com/watch?v=Z8TP3IclXKM

This dood has some interesting tutorials, you might to look around his channel.

Uhm... oops? Oh well... maybe a future project.

I'm a layer whore too. It's a nice piece of mind to know you can change things without messing up things you're happy with... and messing with blend modes can lead to happy accidents.

I swear I've seen something similar to that video before x.x. But... I'll have to look into it. Thanks!