Choose something you are interested in. You will write better if you care about the topic. If the assignment is flexible, consider connecting your topic to a passion, career goal, or something you are genuinely curious about.
Make sure the scope of your topic is reasonable. It should be narrow enough that you can cover the necessary information within the constraints of the assignment, but not so narrow that it is difficult to find supporting information.
Read some background information. Encyclopedia articles like the ones on Credo Reference are a great place to start to become familiar with a broad topic and brainstorm ideas. Credo Reference also has a mind map feature that links each article to related topics and terms, which may help you narrow your topic. You might even try browsing Wikipedia articles, but keep in mind that because anyone can edit Wikipedia there is potential for significant accuracy issues. It is recommended that you don't cite Wikipedia articles in your academic work, however, you may find it useful for becoming familiar with background information or identifying search terms. You can refer to the references page of the Wikipedia article to identify more scholarly work on the topic.
Be flexible! Keep in mind that your topic may change a bit as you work. You may discover something that sets your research off in a new direction or you may find evidence that causes you to adjust your thesis.
Get an idea of the scholarly conversation. Researchers and scholars are engaged in conversation with each other. In their writing, they respond to and build upon each other's work. Authors will reference other studies and articles, and their own writing may even be cited by other scholars in the future. When you write your research paper, you are joining in on this conversation. Browsing different articles and the references they use will give you a better idea of the topics of discussion, different perspectives, controversies, consensus, and current trends of interest.
Still, struggling to find a topic? Reach out to the library for help!