How she missed: Orangey highlights look stark against a dark base color, and if hair lacks shine, as Natisha's did, the color looks flat and dull.
It's a hit! After Frédéric Fekkai lightened Natisha's hair to a soft brown tortoiseshell to accentuate her skin tone and bring out her deep brown eyes, he added fine, golden highlights for contrast and depth. She wanted to grow her hair a little bit, so rather than layer it he used a curling iron to make long waves, which enhanced the gold by separating it out and defining it, while giving her style a shape.
The point: Avoid stark contrasts; boosting shine intensifies color.