The whole art of makeup is about colors and how this colors are combined to produce beauty. You don't have to be a makeup artist or even a painter or graphic artist or designer to know how to combine colors together. It's really that simple. You just have to look at colors that complement each other or contrast each other. Some colors make other colors pop, for instance....if you mix a black and yellow together, the black makes the yellow pop. While a lilac and purple tend to compliment each other.
To get the right colors in makeup application, you have to play around with alot of colors. As they say, practice makes perfect, and in another sense, it's usually fun mixing colors.