Why pink and orange? There are three kinds of red: Blue-Red, Orange-Red and Neutral-Red, also known as Cool, Warm and Neutral. Cool colors are those made with a bit of blue, while warm colors fall into the family of yellows and oranges. Neutral is neither or a combo of both. If you look at a red lipstick, try to imagine if it looks like it's made with a bit of orange, or if there's a bit of blue in there.
Choose which one based on whether the pink or the yellow color next to your face looked better.
From : pintutorials