Visit the Libraries' Research Guides to see what databases are recommended for your field
Use OCLC for comprehensive book searches, if books are important in your field
Indexing only, or full-text databases: be sure that you are not missing older data
What is in an index? Chapters from books? Only journal articles? Popular interpretations, news reports?
Citation databases, like Social Science Citation Index: allow citation tracing to determine important research
Web of Science - Use the "times cited" feature and "cited reference search" to narrow your literature review; create a "citation report" on your literature review topic
Google Scholar- Use the advanced search feature to limit by publication date, journal, author, discipline; use the "cited by" and "related articles" feature to connect to other scholars
Discipline-specific databases will provide more useful information than aggregated databases, like Academic Search Complete
Choose search terms
Become familiar with the terms used in your databases
In EBSCO databases, click "Choose Databases" to refine your literature search to disciplines
Within your database, click on section indicating terms, e.g. Thesaurus (Eric), Index -- Subject Descriptors (EconLit) or MESH (Medline)
For book searching, become familiar with the Library of Congress Subject Headings. Start with a keyword search, and find a book that is on your topic, look at the Subject Headings and click on them to refine your search, or find similar items.
Define criteria for relevance
What is the scope of the empirical materials you are searching for? Subjects, date ranges etc.
What languages are important to your field. Are you using search terms that catch those languages?
Define criteria for methodology
What are the possible methodologies you might employ, do they fall within a discipline, interdisciplinary?
What are the specialized disciplinary sources for this methodology?