Achieve a warmer hue, reminiscent of Jessica Biel's own do, by adding in rich highlights. Select gold highlights if you have auburn or light to medium brown hair. Caramel ones brighten dark brown hair; opt for light blond if your hair is naturally blond. Be careful if your hair is very dark, damaged or fragile. This process can lighten strands up to four shades—a sizeable shift that can be tough on tender tresses.
Steal Jessica's shade: L'Oréal Touch-On highlights in Creamy Caramel, $14; at mass retailers