The Key to Good Research -- Patience is a Virtue!!!
Try using a database like Credo Reference to learn about your topic and help you focus. Background reading can show you the different facets of a topic and provide you with more vocabulary words to use in your searching.
Another strategy is to locate a book on your topic and examine the chapter titles in the table of contents and entries in the index at the back of the book to learn more about aspects of the topic that could narrow your research question.