You should be doing this with everyone!
Whether you are dealing with total strangers or with people that you know intimately well, you should always be asking questions to be sure that you understand the problem that they have or the creative vision that they are trying to achieve. If you don’t understand the total parameters of what you are working with, you might come off looking totally unprofessional if things don’t go according to plan at the end of the day. Always stick to your process whether you are dealing with friends, family, or total strangers off the street.