OK, you got me, there is no magic bullet. The truth of it is that you have to work hard and know what you’re doing. That said, this technique is a handy tool to have in the toolbox – I use it often to get great and predictable results.
I still remember the first time I tried this technique. It was four years ago in Hawaii. It was the perfect sunset, and I wanted to properly expose for both my background (the sunset) and my subjects.
Check out the whole article here: http://www.diyphotography.net/2-stops-underexpose/