Read background sources on your topic. These don't necessarily need to be scholarly. Wikipedia entries can be useful for overview of terminology and context.
Use 2-4 keywords while searching for sources in a database.
Identify 2-4 main concepts in your research question and brainstorm synonyms, narrower, or braoder terms that you can use to search for more information.
Example: Your research question is “Are children who play video games more likely to be violent?” Three key concepts would be children, video games, violence. The table below includes potential alternate terms or synonyms that can be used to search for information related to this topic.
Usually in databases sources are tagged with subject terms. These may be assigned by the database or by the author as a form of controlled vocabulary. Ideally, every article in that database on that topic should be tagged with that subject term. In your search bar, there will be a way to limit to just these subject terms. In practice, sometimes searching just subject terms works well to first identify some of the most relevant articles on a topic, but you'll probably also miss other articles that were not, for whatever reason, assigned that same tag. That's why that iterative search process is important. Trying multiple searches is an important way to identify scholarship that you might otherwise miss.
In EBSCO databases you can identify additional search terms by entering your concept and then typing OR after it. If previous researchers have conducted a booolean search on the topic you will see those an option. This works wonders for some topics and for others it doesn't work at all.