If there is a specific brand you are interested in, including their strategies and branding then you could maybe focus on brand analysis. If you are struggling to focus your topic, maybe these suggestions could help:
Branding and consumer behaviour – A comparative analysis of Pepsi and Coke
As a field of separate study, consumer behaviour analysis emerged during the 1960s. As one of the two dominant global cola manufacturers Pepsi has developed a strong brand of products by creating a wide range of promotional materials. This dissertation analyses different marketing campaigns undertaken by the companies in the last five years and through the use of consumer response survey this study identifies the strengths and weaknesses inherent within them. These, along with the respective market strengths of the two companies are then analysed in accordance with a range of academic theories.
Suggested initial topic reading: