For beginning your search for research articles, consider your research question and identify the key concepts or variables. Then brainstorm keywords and terms related to each concept.
Has declining union membership had an effect on wage inequality?
Wages: wages, earnings, income
Union membership: unions, "labor unions," "collective bargaining"
Generating keywords and related terms will help you start your search. Also, explore subject headings (descriptors) and keywords for articles you find most useful.
Part of deciding where to search is recognizing the differences between tools. The search scopes of Google Scholar, Web of Science, and a disciplinary database are fairly different, but also have some overlap.
Google Scholar searches across resources from all disciplines/subject areas:
Web of Science searches citations of high impact journals in the field (not every journal in the feld, so Web of Science is less comprehensive in regards to discipline).
A Disciplinary Database, such as Sociological Abstracts, searches a defined set of resources, all focused in that field of research, usually this includes: