I'm finishing the hair and did more on the face and clothing. The client agrees that we need to lighten the far side of her face, since it's too dark in the photo. I'm realizing the 'value' of a value guide, especially with the whites of the clothing. A value guide is a white credit card sized card with a hole punched out of the middle of it. Mine is laminated but it doesn't have to be. You place it over an area of the photo reference and see the value of the color in the hole and then do the same on the corresponding spot of your drawing. For me, it usually needs to be darkened, especially on the lighter value areas of the photo. My brain tells me, the clothing is white with yellow-green accents. No where does the photo match the white of the value card. The earring will probably be the lightest area of the whole portrait. The brain is constantly at odds with what the EYE actually sees and what the brain THINKS it sees.
**Thank you for all your suggestions on the previous post. I haven't had time to explore other options, but I appreciate the honest opinions of my family members and blog posters.