For in-depth literature searching:
It often helps to frame your research topic as a question; consider the who, what, when, where and how or how much.
Identify each major concept of your question. You can use these concepts to forumulate your search strategy.
For each concept, consider the most specific terms or key words that you could use to describe that concept. Each of these strings then becomes a single search statement.
A literature review is a survey of current (you determine time frame) literature relating to a particular issue, problem, theory, etc. The review involves a comprehensive search of all of the known/findable scholarly literature related to the issue or topic. The written review provides a summary of this literature and can be a publication in its own right, or may be part of a larger academic research publication.
Formulate the research question
Conduct preliminary search(es) of the literature as appropriate in order to:
Refine the topic
Conduct a comprehensive review of the literature using multiple dabases and other appropriate resrouces
AND narrows a search (more precise; fewer articles retrieved)
OR broadens a search (more inclusive; more items retrieved)