Mixing paint is the same handful of moves over and over. Get them into your hands and you can hit almost any colour you can picture, starting from just three tubes.
Primaries, Secondaries, Tertiaries
You begin with the three primaries — red, yellow and blue — the colours you cannot make by mixing anything else. Mix any two primaries in roughly equal amounts and you get a secondary: red and yellow make orange, yellow and blue make green, blue and red make purple. Mix a primary with the secondary next to it and you land on a tertiary — the in-betweeners like red-orange or blue-green. That's the whole wheel, built from three tubes and some patience. Play with paint A and paint B in the mixer and you'll see blue and yellow genuinely fall into green, not the muddy grey you'd get if you were mixing light instead of pigment.
Tint, Shade and Tone
Once you've mixed a hue you can push it three ways. Add white and you get a tint — the colour goes paler and softer (pink is just a tint of red). Add black and you get a shade — deeper, heavier, more serious. Add grey and you get a tone — the colour stays roughly the same brightness but gets quieter, dustier, less shouty. Slide the three controls in the mixer and watch a single green become mint, then forest, then a muted sage, without ever changing what colour it fundamentally is.
The Three Dials Behind Every Colour
This is the bit worth carrying for life. Every colour is really three dials at once. Hue is which colour it is — where it sits on the wheel (red? blue-green?). Value is how light or dark it is — a tint has high value, a shade has low value. Saturation is how pure or vivid it is — a fire-engine red is highly saturated; a tone of that same red, greyed off, is low saturation. Read the little hue · value · saturation readout in the toy as you fiddle, and you'll start to see colours as three numbers rather than one vague impression — which is exactly the structural way to think.