There are several different mnemonics to help you map your search. Some will be more applicable than others depending on the discipline and subfield your topic fits into.
Clinical Scenarios
PICO: Patient/Problem; Intervention; Comparison; Outcome
PPAARE: Problem; Patient; Action; Alternative; Results, Evidence
Non-Clinical Questions
Concept Breakout: start by breaking your topic into its major concepts. This is similar to what you do when you have a clinical question but you are not confined to thinking about your concepts as either a patient or an intervention or a comparison or an outcome. By doing this you will be able to match concepts to keywords and controlled vocabulary terms and break your topic into discrete, searchable pieces.