First, you'll need to make a few choices.
These questions will inform each other!
As you think about these choices, also consider what YOU are interested in. You'll be spending a lot of time working on this project - you might as well enjoy your subject matter!
Research is a messy process. You may start out with an awesome idea, but it might not be born out in the scholarly literature that you read. It is OK to tweak your topic and to follow an off-shooting path. Don't feel completely stuck with your topic. It's completely normal to adjust as you read and learn more.