Because every topic of discipline has its own jargon, coming up with lists of keywords will be an integral part of your search process. The more keywords you use to search, the more accurate and successful your search will be. There are a few different ways to find the right keywords to use in your search, but the first step is to consider your research topic and start there:
Think about what concepts you are looking for. For instance, a research topic of: the economic impact of International English in France, has three concepts: economic impact, International English, and France.