Academic OneFile is a database offered through the library. This database offers access to over 83 million articles (though not all have the full text attached). For the purposes of choosing and narrowing a topic, we can look to two features this database has: "Browse by Discipline" and "Topic Finder."
The Browse by Discipline tool grants access to topics within specific fields. If you know you want/need to incorporate econ into your research paper, checking the "Economics" topics here can be a great way to start.
The Topic Finder tool is one of my favorite tools for narrowing and solidifying a topic. Enter a broad topic, and the tool provides a honeycomb visualization of subtopics (and even sub-subtopics).
Let's say I want to write a paper about sandhill cranes, but I don't have anything beyond that just yet. I can do a Topic Finder search for "sandhill crane" to get several ideas of ways to focus my paper:
The larger tiles have tiles within them. Simply click on the tile, and you'll be directed to the tiles within it, as well as potential sources to use. Clicking on the Nebraska tile gets me: