Learn to dye your own hair. Check the color match under all possible lighting scenarios in your home, incandescent, halogen, fluorescent, natural etc. Get the blend natural and use some product. Be vigilant about how it looks but not paranoid. Awareness is your friend, anxiety is your enemy.

That being said, I am an art dealer who has spent the last 12 years having to pay close attention to the tiniest of visual details. I can tell you with assurance that when this is done correctly, people cannot tell.