Once she studies your hair, its condition, its style, its cut, and your lifestyle (e. g., how much time you plan on spending on your hair each day), she will then make some recommendations for color and maybe even a more suitable style for you. Plan on being there for a few hours.
When you use the services of a real professional, go to the appointment with an open mind. You may have your heart set of pale blond, but if the colorist can prove to you that a deep strawberry is really your best shade, listen to her. She is trained to match color with skin tone. She knows what will work, and what won't.