This is a question that only you can answer, as the answer depends on your particular interests. However, I can give you an example of how you can go about it.
First, you have to think about a topic you are interested in that can be used in a sociological study. Therefore, it has to be related to the topic of society. An example of this could be marriage within a certain social group, such as teenagers.
1. The question about this could be, "are marriages among teenagers more or less common than in the past?"
2. Some books that you could read would be:
Teenage Marriage: Coping With Reality by Jeanne Warren Lindsay
Teens Look at Marriage: Rainbows, Roles and Reality by Jeanne Warren Lindsay
3. Formulate a hypothesis, such as "Teenage marriages are less common nowadays than in the past."