My friend asked me to draw her young dog, a Belton Blue English Setter. She gave me a photo to work from but it had poor definition (I couldn't see whether the left ear was turned in or had a black patch with a tuft of white fur, and the eyes in the photo were just dark smudges) so I had to google search the breed to get a better idea of the dog's head shape (plus the mouth shape with the bottom jaw is set back a bit, and the eyes seem to be droopy) Still, combining different photos to something similar to the original photo was not easy. I took a photo of the half finished drawing which I thought was better done using charcoal pencils to get some of the grey patch shades on the face:
I find that sometimes when I leave a part-finished drawing for a few days, I seem to get a better idea of how it should look.