First ask the post work do what. After that, ask about their food and housing, what they do after work, to understand the daily expenses, you can estimate the approximate range of wages. Some will also say the company situation and development and so on.
Or before the interview to the unit around the neighborhood, see what people around, such as small stores, security what to talk about, there is hope to learn about some of the situation, so that the interview will have a spectrum.
Said a little bit of their own views. Not necessarily suitable for you.