Photo: Via @georgepapanikolos.
First things first. The level of lightness of your highlights is determined by the strength of the lightener, and how long it’s left on the hair. For the most natural look, highlights shouldn’t be more than two to three levels lighter than the base color, and they should be in the same tonal family. In other words, if the base is warm (dark, golden blonde), the highlights should be warm (buttery blonde). If the base is a cool, sandy blonde, then the highlights should be in the cool family as well, like a light beige.
Of course, the color you choose is up to you, but there are some general guidelines for achieving the most flattering hue for your complexion. If you have pink undertones, then you might want to avoid having warmth in your highlights. It will make you look flushed in the same way that wearing a red shirt would. Check the veins in your arms: If you have green veins and gold flecks in your eyes, then you’re a warm skin tone. You should generally opt for cool tones like sandy blondes, and beige blondes.
If you have an olive skin tone, blue veins, and silver-grey flecks in your eyes, then golden blonde tones will bring warmth to your face, and make your skin appear less green. Try buttery blondes, honey, and strawberry.
If your skin tone is neutral and has no pink or green, then (lucky you!) you can go for either warm or cool blonde hues.