Read a general encyclopedia article on the top two or three topics you are considering. Reading a broad summary enables you to get an overview of the topic and see how your idea relates to broader, narrower, and related issues. It also provides a great source for finding words commonly used to describe the topic. Write these keywords down; they may be very useful to your later research. If you can't find an article on your topic, try using broader terms and ask for help from a librarian.
For example, there may not be an article on "social and political implications of Jackie Robinson's breaking of the color barrier in major league baseball" but there will be articles on "baseball history" and on "Jackie Robinson".
Use databases to scan current magazine, journal, or newspaper articles on the topic.
Use Web search engines such as Google to find websites on the topic.