The best tool for developing your topic is a database. Let's say you're interested in writing your paper on autism spectrum disorder. Searching for that term will likely retrieve thousands of results.
Look through the first couple pages of results to see what subjects interest you. For example, how autistic individuals interact in social settings. Entering “social skills” into the second search box. Narrow these even further by entering a third search term, “play.” Results have dropped considerably!
You can also cut down on the number of articles you retrieve by using the search filters in the left column, such as age and subject headings.
And the articles themselves can lead you to more research. Article records are full of live links. When you find an article you like, there are several ways to find similar articles.
You also need to consider a more conceptual approach to your search. What is your approach to your topic? If you're looking at autism spectrum disorder, are you looking at
Instead of using just one of these to narrow your search, think about using several of them in combination. In other words, rotate your viewpoint. By looking at your topic through the lens of a different approach, you'll be able to enhance your initial concept and find a new set of articles.
Consider approaches such as assessment, environment, and impacts on different populations, then pair these up with your topic. For example,
By changing your search topic and keywords, you can search from every point of view and discover what research is available.
And if you're still having trouble finding enough good sources, contact your subject librarian for help!