This is a great question. There are a few ways in which to approach the topic of popular culture. Let me name a few of them.
First, perhaps the most fruitful way to approach the study of popular culture is through sociology. Sociology will give you great theoretical tools to study how societies work. For example, scholars like Peter Berger have done amazing work on things like sociology of knowledge, which can help tremendously in studying popular culture.
Second, another avenue towards studying popular culture is to explore the field of cultural anthropology. Like sociology, cultural anthropology will give you tools to see society and culture from different angles. In addition, cultural anthropology will help you to ask the right questions, as you examine your own culture in light of other cultures. The comparative approach can be exceedingly fruitful.
A final way to study popular culture is through history. By studying popular culture of the past, it can give you insight into popular culture in the present. It can also show you how movement rise and fall. Moreover, history can incorporate the insights of sociology and cultural anthropology.