I deleted the original post after deciding to do some cleanup of masks and adding a couple of adjustments. For one thing, the eyes were too bright and didn't have any natural color. Eye whites are not actually white, you know? And I fixed the eyelashes as well.
On Twitter I follow a couple of accounts that post old b/w photos, mainly of Hollywood stars of the past. This one didn't have any identification of who she was, but when I submitted it to Google's photo search, it correctly suggested that it was Hedy Lamarr.
I chose this photo to practice on because it was large enough that I could get some finicky details that would be harder just looking zoomed in on a small photo. I probably took way longer on it than more experienced people might take, but I'm satisfied with the result.
There are Selective Color adjustment layers for each element: skin, dress, eyes, lips & nails and hair. And one for the background. There was enough hair detail that the new Select and Mask feature in #PhotoshopCC came in very handy when selecting her hair. In addition, there is a Hue/Sat adjustment layer attached to each Selective Color layer because, in the end, it was just easier to tweak the hue and saturation levels that way once the base color was done as close as I could get it with Selective Color.