where to dodge and burn
I spent a few minutes just searching for this type of information and ended up with some interesting articles and videos. You just need to filter out the results that show you how to do it and look at the ones that show you why.
In addition to the goal of bringing out detail in extremely light and dark regions, one other particular suggestion I liked was to control the viewer's attention, ie. to draw their eye to a particular area--- think vignetting only asymmetric. I also stumbled upon some fairly creative applications in portrait retouching. So I think there is quite a bit of free content that will at least give you some new ideas and examples.