1. Mixing Foundations
2. Adding An Illuminator
Depending on the type of finish you want, you could mix a liquid illuminator in with your foundation. If you like a dewy, glowing finish this is the way to go. You get that highlight you love and the light pigment of the illuminator dilutes the darker foundation.
If you have never tried a liquid illuminator, these are my favorites: MAC Strobe Cream, Smashbox Illuminating Serum, Benefit High Beam. For a more affordable option try NYX Born to Glow for £7.00 from Boots.
Note: Decide what works best for you. Some are neutral pigments (white) and others look pink or warm. Pink tones work best on lighter skin, gold tones for darker.