No one handles edges better than Chris Saper. Look at her
portrait of Linda for a fine example of diffuse edges. Masterful work!
I'm still an amateur myself, so consider the source, but I see a lot of painters who add hard edges where there are none in the photo. Sometimes, even when there are hard edges in the photo, you can soften them to improve the image.
One of the SOG artists (can't remember who) says that we're not painting stuff. We're painting the way light bounces off of stuff. I may have butchered the quote, but the point is that we should move beyond rendering details, and paint the light.