Foundation can look grey if not chosen properly. Avoid shades that are too light. Undertones tend to have different color variances ranging from light to dark, so you may need to blend and mix a range of shades for different areas of the face. People with deeper skin tones tends to be darker across the brow and chin and somewhat lighter on the cheeks. To even this out you may need to apply a lighter foundation on the forehead and chin and a little darker shade on the cheeks. Learn more about finding the right foundation shade.
Concealer can be used under the eye or to lighten up the forehead or chin. Foundation is your all-over color, and is to be used to even out discoloration on the skin. If the skin is medium tone, choose a foundation with a yellow and peach undertone like chestnut and tawny. The tawny range will blend better with the undertones that have more of deep red warmth. Try Pressed Base in the chestnut range when working with undertones that have more of a sallow color to neck and face. This will even out the yellow in the skin. You may also want to blend the chestnut around the perimeter of the face then the tawny on the cheeks and nose area. This will give a beautiful finish with a natural effect. For a very deep skin tone, use a foundation that has a slight blue cast like cocoa.
*Precision Eye Pencils can double as a lip pencils for darker skin tones. Brown and deep plum work especially well