When searching a periodical database, like ProQuest or Academic Search Premier, your goal is to get a reasonable number (around 50) of highly relevant articles. To do this, use the Advanced Search feature to combine keywords (names, places, events, ideas, synonyms, etc.) specific to your topic. Here is an example for setting up a search in Academic Search Premier:
If you've never used the databases, watch these introductory videos:
How to search Academic Search Premier
For help with setting up and focusing your search, watch Advance Searching Techniques.
Other ways to focus your searches
√ Define a date range (for example: 2005 to 2013)
√ Use their "Suggested Topics" or "Find More Like This" feature
Also, watch this video from Kent State University: Talking to Databases