ProAdvice

a few tips from Robert Bachelor:
Good communication is the best way to ensure getting the hair color you’ve had in your ‘mind’s eye’ out of your imagination and on to your head. Hair cuts can be described with words and hand signals, “...no shorter then here!”, but the best way to communicate color is with pictures. This is because each of us perceive color differently and the words we use to describe color can have different meanings.
For example, is a stick of butter yellow, cream colored, warm beige or the color of a pale winter sun? Now imagine how hard it would be to describe a specific color of red hair. This is why it’s so important to make certain you are both "seeing" the same color.

I recommend bringing pictures of your favorite color to your stylist/colorist. If you have several examples, even better. And the pictures don’t have to be just hair. How about a picture of iced tea sitting in the sun to convey the concept of light golden brown, or a picture of a gemstone, such as a Tiger's Eye, to convey the colors you want in your highlights. I had a client bring in a picture of a wheat field to describe the ‘natural, earthy blonde’ she was looking for.

“A picture is worth a thousand words” can be taken literally when it comes to coloring hair.
Before any color is pulled from the shelf and mixed into the bottle, it is imperative that you and your stylist are sharing the same vision, leaving less room for "interpretation."