5. Find the Right Formula
Foam dyes like John Frieda's Precision Foam Colour (left) are best for women with sensitive skin, since the mousse-like formulas won't drip onto the face or hairline. According to cosmetics chemist Ni'Kita Wilson, women with thick or curly hair will have better luck with gel or liquid formulas, like Kelly Van Gogh's Master Blend (center) and the L'Oreal Excellence Creme (right), which provide full coverage and distribute efficiently throughout the hair.
John Frieda Precision Foam Colour, $13; drugstore.com
Kelly Van Gogh Master Blend, $39; trykellyvangogh.com
L'Oreal Excellence Creme, $9; drugstore.com