When choosing search terms, try to identify the most unique words that are likely to appear in a written document on your topic.
Here is a list of terms that appear frequently on the Global Nonviolent Action Database. You might want to try using some of these terms while researching cases.
What other words could describe the case(s) you're researching? What words might a participant use? A sympathetic journalist? A scholar?
What about a less sympathetic journalist? A company spokesperson? An opponent?
Are there culturally-specific or movement-specific terms that would be used by the activists you're researching?