Foundation, and if you use concealer too, needs to match your skin tone to look as natural as possible. This is something we all know and are taught the very first time we use foundation. I can remember my aunts, who I always begged to apply makeup on me while I was visiting them, telling me I had to make sure my face matched my neck. This usually meant throwing some powder on my neck and blending the foundation into my neck, and they powdered me up pretty liberally.
What my aunts didn't realize back then was, if you matched your foundation to your neck, rather than your face, you wouldn't have to blend that far down. Simple enough. Your neck is more guarded from the sun than your face so will usually be slightly lighter than you face. Also, your face will darken when you put concealer and foundation, even before your powders and bronzers. The trick is to get a foundation that matches your neck’s skin tone or even one shade lighter.
Many stores, like Sephora and Ulta as well as the designer makeup counters in department stores, allow you to test the colors and find your perfect match. Avoid testing colors on your hand or arm only because the skin here will usually be even darker than your face. If you need or want to use a concealer too, make sure that’s lighter as well. The more layers, the layer the look.
Sure, you can do what my aunts told me, “Blend it in, Honey. You don’t want a contrast line on your neck.” Or, you go a shade lighter and not worry about that defining skin tone line along your jaw. It just won’t be there.