A critical first step in beginning any review is a well-defined, searchable research question. Several frameworks have been developed to assist with the process of defining the research question. PICO is the most familiar in the medical field, but it is by no means the only option. See below for more information on a few of these frameworks.
Wildridge, V., & Bell, L. (2002). How CLIP became ECLIPSE: a mnemonic to assist in searching for health policy/management information. Health Information & Libraries Journal, 19(2), 113-115.
PESICO (originating in augmentive/alternative communication)
Schlosser, R. W., Koul, R., & Costello, J. (2007). Asking well-built questions for evidence-based practice in augmentative and alternative communication. Journal of Communication Disorders, (3), 225-238
SPICE (originating in library and information science)
Booth, A. (2006). Clear and present questions: formulating questions for evidence based practice. Library hi tech, 24(3), 355-368.