KEY COLOR NOTES "This is just such a bright sexy blond," says colorist Denis De Souza, who works with celebrities like Mila Kunis, Olivia Wilde and Rachel Bilson. "To make it work for fall, just be sure to amp up your makeup a bit. That way you won't look washed out." De Souza also points out that because the tone is slightly ashy, it's best reserved for women with fair skin. "Otherwise you get too contrast-y," he adds.