How do I mix colors together?

The three arguments to the tweak palette command are Red, Green, and Blue (That's why you speak about RGB colors)

Example

tweak palette (30,0,0) # more red
tweak palette (0,30,0)# more green 
tweak palette (0,0,30) # more blue

For the other colors, you need to understand how to mix light

red + green = yellow red + blue = magenta (purple) green + blue = cyan (blue-green)

To make the color brighter; increase all the three primary colors and to make a color darker, just do the opposite: decrease all the three primary colors.

Note that if you decrase a color, the other colors look brigher in comparaison.

For example :

tweak palette (0,0,20)

Less blue but the red and green are still here. So red+green=yellow so less blue means more yellow.

The best way to understand how color mixing work is practicing. Try different combination and see what happens. If you had both green and red gives you yellow. Then add a little more red and you get orange.