Remember, if your hair has been colored it would be slightly harder to determine your appearance type. Also, while determining you should not wear any make up on your face. It’s better to put on neutral colors clothes without accessory. The best lighting for real colors is a diffused day light.
At first you need to examine your skin tone: is it warm or cool? It’s quite easy; just try on some golden and silver textiles near your face. If silver fits you more, so you have cool skin tone. If golden better interacts with your skin, so your color harmony is in warm. Neutral skin tone owners usually have complex colors in their appearance, so they need to determine their undertone also. Do you think your skintone and undertone features look like Amanda Seyfried's? Just have a look on best and worst Amanda Seyfried's make-ups for her light skin tone with cool pink undertone to have your inspiration! It will help you finally to determine your skintone as cool or not.
The undertone color looks to shine through your skin. How to determine it? A good piece of something white, towel for example, will help you to test your skin undertone. Test it only with diffused day light because even small amount of artificial light, such a monitor or table lamp, will add hues to your real skin color. Bring the piece of something white close to your face. Does your skin look bluish, greenish or yellowish, or maybe pink? Blue and pink are cool undertones, yellow from peach to golden is about warm undertones, and people with green undertone usually have neutral skin tone.
Why does it important to determine your skin tone and undertone? It will help you to choose an ideal foundation, concealer, blush and powder, which will look absolutely natural on your face. Also the undertone is exactly the thing that helps match all make up perfectly by choosing the same undertone in eye shadows, lipsticks and lip glosses. You just need to choose foundation in according to your skin tone taking into account the undertone (blue, pink, yellow or green).
The last step would be determining the color intensity of your skin from light to light tan: