What an intriguing project...
I am doing ghost story pictures based on my favorite Japanese artists, but never thought about photos of relatives I didn't know. I would usually try to figure out what I remember than read about the time period or read bios or histories similar to the time.
For a three "card" draw:
My suggestion is to look at the photo and pick one element--say a hat or scarf--then write a note.
Card number one is past or starting point and is the key to the past.
Use the deck you are most comfortable with to act as a second point and then draw one card. Card number two is opening the lock.
For me, I would write any parallels or contrasts and a keyword like hat.
Then number three is the keyword discovery--look for something you didn't know. Through google, library searches, talking with a relative, what about the hat, scarf, person of that age or time? If all you have is a name, do a name search or write why was the name chosen or what could this mean? A casual thing like being named ___ can tell one what was popular at the time--a king or queen or singer or actor with the same name at the same time might yield something interesting.
Good luck!
Cerulean
P.S. My husband's family tree yielded many Marys in confirmed names, but only one in a given first name in a generation. They were Irish Catholics.
James was also a popular name, curiously.