My hair is naturally a light ashy brown, but it's been dyed a few times in my life. Right now it's a medium/dark brown. I'd like to dye it a natural, dark ashy/champagne blonde with maybe some highlights added later, but I'm afraid it would end up looking brassy and orange because of all the dye in my hair. How do I avoid this? (I'll be going to a salon, not doing it at home).