Capture the Light
Your photographer will be skilled at capturing your joy in perfect natural light. Your job is to add the proper amount of light-reflecting highlighter and shimmery cheek colors to make their job even easier. Always apply blush and be sure to apply a bit more than you would normally for everyday life.
Use a cheek brush to apply color to the apple of the cheeks and move the color back softly back to the hairline. Be sure to pick a blush that will reflect the light, and skip anything too matte. Nars does a great job with this type of cheek color. My favorite is Nars Blush in Super Orgasm ($30) for those with medium or darker skin tones and Nars Blush in Orgasm ($30) for those who are fairer.
Add highlighter to the high point of the cheekbones, and on any other feature of the face that you want to stand out. This can include above the middle of the lips, above the brow bone, and down the center of the face. My favorite highlighter that works on just about everyone is Becca Cosmetics Shimmering Skin Perfector Poured Creme Highlighter in Champagne Pop ($38).
It helps to practice at home, and be sure to take selfies to see how the flash captures your glorious cheekbones.