First of all, you should make clear what is the center of your investigation, what will be related to this investigation center, and then set questions. When setting questions, don't involve personal privacy, don't be ambiguous, and the language should be clear and direct. The finer the questions, the more realistic your conclusions will be.

Take a shopping mall consumption grade survey as an example;

It involves job category, personal income, educational background, age group, number of family members, location of residential quarters, ownership of private cars, key consumption categories, average monthly consumption quota, favorite brands and even preferred vacation places.