I usually start by pulling down on the left usually at about the point show in the curve in post #1. I always have a hard time deciding were to start when pulling the mid-tones. There are many of my images were I don’t adjust the top of the curve at all.
When I make the left side adjustment I watch both the image and the curve. Often, but not always, the curve will fallow the contour of the histogram. Then I can use that to help guide adjustment on the right side always watching the effect on the image.
I use Levels and Curves as a global adjustment so I am trying to set the overall contrast and give me a good starting point for making more localized adjustments using controlpoints.