I use the dodging and burning tools to lighten/darken areas. However, I've found it very easy to overdo it or run off the edges with this tool (and lighten or darken the wrong area). I'm sure there is a better way to do it but I am by no means a PS expert. Can you select a subset if your picture for lightening/darkening without running the circular cursor over everything? That seems too prone to human error. Please advise!