Cool Undertones: Understanding skin tone is the key to choosing the right blush color. Cool undertones contain more blue and are seen in choices such as red, pink and mauve. Tip: Before you apply foundation, flush the apple of the cheek with a bit of color to give the skin a nice glow. Then, when you apply the blush, keep the red toward the apple of the cheek. It creates a look similar to what you get after having a glass of wine.