I used to shoot almost exclusively in Av mode. Lately I've been trying to shoot predominantly in Manual, mostly so I am forced to think more intentionally about my exposure. I've found this has helped me when I do use the Av or Tv modes, as I do what Scott describes with the exposure...
If you're just doing spot touch-ups, you might be better off using Lightroom. I only use Photoshop if I have to clone or heal large swaths, or do more graphic-y type things.