Doing some background research will help you uncover related concepts and synonyms to use as keywords when searching for scholarly, peer-reviewed articles. It is also a good idea to gain some basic knowledge on your topic and learn the vocabulary of the experts before diving into scholarly literature.
Recommended Databases:
Using a database thesaurus (when available) instead of keywords can help you find relevant articles without having to know all the terms authors might use to discuss the same concept. This video explains how to use the thesaurus in PsycINFO, but the ERIC thesaurus works the same way.