Research teams should partner with a librarian to design search strategies. Librarians are experts in translating research questions into search concepts, identifying appropriate databases, developing comprehensive search strategies, translating the search strategy for each database, writing the search methodology, and creating the PRISMA flow diagram.
The National Academies of Sciences, Engineering, and Medicine (formally the Institute of Medicine) has issued standards for systematic review teams in the book, "Finding What Works in Health Care: Standards for Systematic Reviews" including standards specifically for conducting searches:
Searches should seek high sensitivity, which may result in relatively low precision.
Recall (Sensitivity): The number of relevant reports identified divided by the total number of relevant reports in existence
Precision: The number of relevant reports identified divided by the total number of reports identified.
For more info, see: Higgins JPT, Green S (editors). Sensitivity versus precision (section 6.4.4) Cochrane Handbook for Systematic Reviews of Interventions. Version 5.1.0 [updated March 2011]. The Cochrane Collaboration. Available from http://handbook-5-1.cochrane.org. Accessed June 1, 2018.