I would fill the hair first with a lighter shade of brown before putting the darker color on the hilighted pieces. The developer should be diluted in half with water to a 10 volume as you only want to deposit color and not lift the hair anymore causing more damage on the ends. watch the ends and spray with water and rub with a towel to check on how the ends grab the color. Then you can put the darker color on. This is a corrective color and I would have it done prefessionally if you aren't a stylist. If you are a stylist I would do it like that. I was a stylist for 10 yrs and worked for Aveda, Regis, and such. Color was my specialty. Nwo with 4 kids I am at home with them.