Brunette or black hair: Kirsh recommends that people with dark hair stick to what she calls " Crayola crayon yellow," a very true version of the color. It shouldn't be muddled or muted, but a shade that comes right off the primary color wheel.
Auburn or reddish tones, warm golden brown hair: Those with a hair color similar to Julia Roberts' should wear very warm, golden yellows. They do well with mustard and muddled, earth-tinged yellows.
Warm blond, champagne or flaxen blond hair: "Go brighter," Kirsh says. "Like a canary or lemon shade." It shouldn't scream or be fluorescent -- you want something vibrant and defined.
Platinum, ashy blond or gray: An icy pastel works best here. The shade should be more faint, cool and dusty rather than loud and bold.