Hello. I want to color my hair at home. My hair is originally dark brown and I always like to lighten it to a light brown. I've accomplished this with grocery store hair color in the medium/dark blonde range but now I have a few gray hairs that are not responding to this product anymore. Some of my friends use Shades EQ but they get it done at a Salon. I want to do it at home. What formula can I use to accomplish a very light golden brown color? Thanks in advance!