In terms of mixing colors with paint, instead of thinking of 3 primary colors, it can be helpful to to think about 6 colors.
By thinking about the primary colors as a set of 6 split primaries, many possibilities open up for us. The one most often cited is the mixing of colors. This was well elucidated in the book “Blue and Yellow Don’t Make Green” I will give a brief description of those ideas, but I do recommend the book.
The next point – and this is big – is now we can start thinking of color movement. Instead of thinking of colors as static, think of movement, and how colors relate to each other around the color wheel.