Start by phrasing your subject or general topic in the form of a question.
Then ask yourself further questions about your topic:
-What do you know about it? What don't you know?
-What interests you about a potential topic? Are you enthusiastic about it?
-Think back on previous classes, discussions, programs, readings, etc. Is there an issue or topic from those experiences that can influence your topic choice?
-What aspects or viewpoints of your topic interest you? Examples include social, legal, medical, ethical, biological, psychological, economic, political, and philosophical. A viewpoint allows you to focus on a single aspect.
-What time period do you want to cover?
-What place or geographic region do you want to cover? Examples include national, international, local social norms & values, economic & political systems, or languages.
-What population do you want to cover? Examples include gender, age, occupation, ethnicity, nationality, educational attainment, species, etc.
-Next, look for resources which provide background information. Some selected general and specialized subject sources can help narrow the topic.
Remember, there are two layers of research:
1) a broad search to discover resources and to read some background information
2) specific searches for information once you've focused your topic.
You may also want to consult ideas on the University of Richmond's Writer's Web.
Link to Narrowing Your Topic: 5 Quick Tips