The Jehovah's Witnesses are always polite and always leave several free publications which contain articles on a variety of topics. I scan the publications, highlight areas of interest and file them for future use. Visitors provide an opportunity to utilize all of your senses as you gather your information. Observe their physical characteristics, their mannerisms, their dialect and personality traits. Turn the tables.
People love to talk about themselves.
Within five minutes you will have their whole life history. Understand what they want from you and why. Associate as many adjectives as possible with your visitor and write them down as soon as they leave. Then describe the behavior that prompted you to use that adjective. You will have the basis for a character in your next short story or novel.