Formulation:
You definitely want to get a bit of sheen on your cheeks. You want the skin to look dewy and young. Ideally, if you have normal to dry skin, I suggest giving cream blush a try. This will give your cheeks color while adding a bit of sheen to catch light. If your skin is oiler, a cream blush most likely won't work. The oil in your skin will breakdown creamier formulations faster and diminish their color effect. I'd suggest a powder version that has a touch of shimmer which will mimic this effect.
Color:
You want something juicy and healthy. Try very 'fruity' shades that might look a bit bright in the package. Use a great apricot, strawberry, or cherry color to make your skin look radiant and lit from within.
How to apply:
Cream blushes are best on moister skins to make the color blend easier with no splotches. While your moisturizer (tinted, perhaps) or foundation is still pliable, use your fingertips or a sponge to dab and circle color onto the apple of your cheeks. Smooth the blush up and back toward your temples. If you apply powder to set your make up, do this after and over the blush. If you're using a powder blush, my tip is to use a really fluffy brush. Swirl color onto the brush and dab and swirl blush on apple of your cheeks, sweeping up and back toward your temples.
A couple shades I love for summer are:
Cream Blush: The Multiple by NARS (can be used on cheeks, eyes and lips) in shade 'South Beach'

Powder Blush w/Shimmer: Cover Girl Cheekers Blush in shade 'Golden Pink'

Brett's Tip:
When I'm working with an actress or model I always have them smile when I apply blush. This brings out the apple of their cheeks and guides me to the perfect, most natural placement for color.
Blush on ladies and as always...
Enjoy Pretty,
Brett
VANITYMARK Cosmetics