Scan the picture at the highest resolution possible. Then use photo editing software to crop a face, the address on a house, or a license plate to get a better look at it. This isn't meant to be a step-by-step tutorial, but I will mention that Picasa is a free photo editing software and Adobe Photoshop Elements is one I bought. I use and recommend both.
I also cropped the license plate on the car and could tell the date on it was 1942.
Since she was born in April 1940, that gave me her approximate age when the photo was taken.