My suggestion, if you're trying to avoid damage, is to use a demi-permanent dye. The only downside is that demis will not lighten hair, but they will change the tone of your hair beautifully if you want to add a caramel hue or whatever. They also gradually fade out, leaving no line of demarcation where your roots grow, and it lasts a long time. Any time you lighten your hair at all, you are lifting color out of the strands, and that will do more damage. Demis also happen to cover gray, if you have any.