My advice is to have a friend come over and help. Any hair longer than about two knuckles is really hard to color by yourself.

My other suggestion is to go to the Aveda Institute - they have trainees that will color hair on the super cheap.

If none of those workout, buy two boxes of color. There is never enough in there for long hair, and curlier hair takes more. I've used every brand there is, with no damage, but it depends on the hair you are starting with.