This is why I draw in black and white in real life, but use color when drawing in the computer; on the computer, I can type in the values for a color (such as 255 0 0 for red, and then, when wishing to make it fade darker, slowly knocking it down to 240 0 0, 220 0 0, 200 0 0, 180 0 0, or when wishing to make it brighter to pink, 255 50 50, 255 100 100, you get the idea; I am able to accurately determine any color through it's RGB values, and even produce varieties of tints and shades.