Prior to starting a systematic review it's helpful to find out if a systematic review has been done or is under way. Published reviews also provide a starting point for identifying studies in your area of research.
Some databases focus specifically on indexing evidence-based medicine, systematic reviews, etc. e.g. Cochrane databases
You can also search the larger subject databases such as MEDLINE, CINAHL, PsycINFO and limit the search to "systematic review". Some databases have a filter or limit option to limit the search to 'systematic review'.
It's also useful to search the large mulitdisciplinary citation databases Web of Science and Scopus, particularly if your research is cross-disciplinary.
1. Identify main concepts and keywords. Search the main concepts first, then limit further as necessary.
2. Find Synonyms (Boolean OR broadens the search to include alternative keywords or subject thesaurus terms):
3. AND (Boolean AND joins concepts and narrows the search) :
4. Be aware of differences in American and English spelling and terminology. Most databases use American spelling and terminology as preferred subject terms.
5. Use Truncation (putting * at the end of a word stem will search all forms of the word):
6. "...." (inverted commas) use for a phrase
7. Wildcard ? will search for any single letter in the space. e.g. wom?n will search women, woman, organi?ation will search organisation, organization.
8. Wildcard * can also be used where alternate spelling may contain an extra character. e.g. p*ediatric, will search paediatric or pediatric, behavio*r, will search behaviour or behavior.