Highlighting healthy hair

One of my friends used to have a damaged hair from coloring and highlighting it so much and it has become dry! So, she started to take care of it and when her hair becomes healthy and strong, she thought about highlighting it… at first, she was a bit scared of using chemical products to her hair that has just started to become healthy… so, she asked an expert and he advised her positively, and ensured of no such troubles as long as she keeps on taking extra care of her hair… he suggested her to highlight her hair at a salon so that a professional monitors the process… he also advised her to insist that a strand test should better be performed to ensure herself that her hair is capable to withstand the chemical treatment without being damaged… besides, with the strand test, the stylist will make sure of the exact processing time for the hair to absorbed the treatment…