I believe in enhancing or de-emphasizing, not necessarily removing, unwanted physical characteristics. Too many photographers remove the wrinkles and skin texture. I tell my clients that I will make them look rested, not 17.
A few of the methods I use in Photoshop follow. Always create at least one retouching layer.
Lighten whites of eyes or irises: Brush, opacity 7, mode lighten, foreground white
Alternate: select eyes and change levels with mask to hide other stuff.
Define eyelashes, lips, etc. Brush, opacity 10, mode multiply
Whiten teeth: Brush, opacity 12, mode color, foreground white
Alternate: Brush, mode lighten, 7-15%
Alternate: Desaturation sponge. This may result in a graying down of the area.
Darken: Brush, opacity 20, mode Multiply, black or white in foreground