You're Making Me Blush!

One of the 2 things I cannot live without beauty-wise is blush (the other is mascara).
Blush is used to emphasize and contour your cheek bones, and give you a younger appearance. Women have been pinching and slapping their faces for centuries to redden their cheeks. During WWII women in camps pinched their cheeks to make them look healthy. So basically, blush saves lives :)
One of my favorite blushes is the Nars line. Specifically "Desire".

"Desire" gives you a "just came in from the winter cold" look.

I'm sure you're looking at this and thinking, "That looks like something from the 80's!". And you'd be right. Blush colors haven't changed much of the last couple decades, but the application has. In the 80's we (if you were around for it) used blush to excessively highlight our cheekbones. For example, check out this classic 80's beauty:

In order to have a natural, healthy blush apply to the apples of your cheeks first (smile really wide), then go lightly up the cheekbones.
I always match my blush to my eyeshadow--bright pinks to cooler tones, corals and peaches to warmer.
 You can also get blushes with highlighters in them as well. I do like this, but have a tendency to stay clear as my bronzer is a bit shimmery already.

MAC "Daft Pink"

 I happen to think that all blushes are made equal, expense wise. I do have a couple higher end brands, but drugstore blush works just as well. As long as you use a sealer it'll last all day and well into the night.

Left: Cover Girl in Rose Silk
Right: Cover Girl in Classic Pink

And if you're lucky enough to be one of those people that naturally blushes often, good for you! Blushing is a sign of endearment and being lovestruck :)