whitehorse
I find that having introduced myself I let them talk a little about themselves, and try to find out what they want to get out of the flight.
Including where they live (they might want to see their house from the air), have they flown in a light aircraft before, what their interests are (one elderly man was a keen gardener and I was able to show him a private estate with all the bushes in bloom). I then give a quick potted history of my flying experience. It only takes a couple of minutes and then I modify my brief accordingly. It saves a red face at the end of the day.