Can anyone help with this portrait I'm working on? I think the shadow side needs reflected light, but I'm not sure where or what color to make it since I don't really see reflected light there in the reference photo.
One thing I have done, and it looks like you can do it here. . .
make a copy of the photo, or a layer in the same photo, depending on if your software can do that, and brighten the heck out of it to find the edges of the jaw and so forth. Do that for finding the geography of the face. It'll look like hell as a photo, but it's only use is to provide info for your painting.
You can place that on a layer over your painting to see where things go and make a layer to paint the backlight on top of that. Just turn the info layer off later when you no longer need it.
Remember this old real estate saw, 'location, location, location'. . .
The other thing to do is find a successful picture/painting with the kind of lighting you want to achieve. So between getting how to handle backlight, and the accurate placement, you should be in bidness, Texas.
'Course, if you get the model to pose again that would be handy. You could do that and light it from the back too.
Or you can get a 'stand in' and light them, or even use yoruself as a stand-in. And of course, once you have that supplimental shot, apply it appropriately to that guy's pic and make it work.
Good luck. I think you can do this. Your original reference is not entirely gone in that area.
Oh, and next time somebody asks you to tackle a picture without decent reference, give them a 'surely you jest' look and jack your price way up for emphasis.
i avoid black (almost) at all costs.. the flesh color on the light side is basically shades of pink or orange.... the complimentary of these colors are blue and violet.. toward the red violet to warm it up or blue violet to cool it.. try these colors as dark as you like but retain some of the color.. to darken a color add a little of its complimentary as an underpainting where the shadows form.