For intricate outlines, the Edit Selection tool is best. I use it for birds, leaves, flowers, etc. For smooth outlines, I find the Object Extractor is good and Flood Fill is great to color in the interior. It gets it all without having to edit the small misses.
As you demonstrated in the Basic Extraction webinar with the apple, flood filling the transparency part with white, makes using the Eraser tool easy to use to remove the unwanted parts of the extraction.