ahh thank you so much! ♥ welcome to the digial art scene friend, i hope you enjoy your stay and ctrl + z
now onto your question! (if you don’t know what layer and layer modes are and how they generally work you should probably google that before you continue reading)
we all perceive colour differently (thx science) and i trust my intuition a lot when it comes to colour picking because of that, and also because i feel like you can make pretty much every colour combination work within the right context. context is key! but still, remember that all of this is about how i perceive colour, so you might not agree with everything i say.
here’s a quick rundown of terms you’ll see around a lot in reference to colours and shading: the hue, which is the ‘colour’ itself, the saturation aka the intensity, and the brightness [or value] which describes how dark or bright we perceive a colour to be.
rule of thumb: when you shade don’t just add black (or white) to your base colours, that will make your drawings boring and lifeless. use different hues and saturation!
now first things first: which skin colour does the character have?
you’ll mostly be navigating in the red to yellow spectrum for the skin tone. so when i pick the base colours i usually start with the skin and adjust the rest of the colours accordingly. if you’re not sure where to begin it might help if you first determine the values (brightness) of the base colours in grayscale.
and here are a few colour variations—i stuck to the approximate values but played around with a lot of different hues and levels of saturation.
now compare 3 and 5: you’ll notice that 3 is very bright and leans towards orange hues, whereas 5 has a pinkish tint.
on the left i gave 5 the hair colour of 3 and in my opinion the pink hue of the skin doesn’t go well with the orange undertone of the hair. you’ll have to experiment a lot to find out which combinations work for you.
ctrl + u is your biggest friend (or image >> adjustments >> hue/saturation in photoshop, the shortcut works in sai and clip studio paint too). play with the sliders and see what happens. i do that a lot myself, because it’s easier to coordinate the colours like that afterwards instead of trying to manually pick perfectly matching ones right away.
for further adjustments i like to use an extra semi-transparent layer on top of everything with just a single colour to add atmospheric light. this unifies the colours and makes them more harmonious, if that’s what you’re looking for. this is about as far as i’d go if i didn’t want to shade the drawing.
if i do want to shade, especially with high contrasts and dramatic light, i darken the base by just adding an additional black layer, here set to 40% opacity. of course you could add a colour layer like the ones i mentioned previously too.
to create an impression of dramatic light you need a high contrast between light and dark areas (1). if i want additional visual intrest i often add secondary light which falls onto the main shadow areas. here i picked a faint greenish blue to balance out the yellow (2). and since light is at least partially reflected when it hits a surface you should add a faint glow that goes across the shadow/light border (3).
for this shading style i like to use the layer mode colour dodge with lowered opacity + fill settings. for some layer modes opacity and fill do the exact same thing (e.g. for multiply or screen). however for colour dodge there’s a big difference:
a lowered opacity merely alters the transparency of the entire layer. that looks pretty awful sometimes, because the bright orange affects the dark of the hair much more intensely than the already brighter skin. but when you lower the fill percentage you primarily lower the amount of light that falls onto darker colours. so the layer’s opacity setting treats every colour equally whereas the fill setting takes their values into consideration. it might be hard to understand if you don’t try it out yourself, so just play around to get a feel for how it works!
and to summarise, here’s a process gif:
colour is an extremely big topic and i’ve only barely scratched the surface but i hope that still helped you out a little! the fastest way to learn is always to try things yourself, so grab a sketch and experiment. 👍