Searching can be time consuming and frustrating.  A carefully constructed search is most likely to locate good evidence.  We use the following structured approach. However, experienced searchers realize that flexibility and trial-and-error are often necessary to find what you are seeking. 

1) Execute a search filter for the type of information you are seeking
2) Perform a seperate search of the intervention (or diagnostic test)
3) Perform a seperate search the disease
4) Combine 1 AND 2 AND 3
5) Limit or expand your search as needed

Note that each of the components of the search is built up by doing individual searches combined using the OR term. We made use of the OVID Mesh browser to select some of the terms

Below is an example search performed in OVID.  We were interested in finding references on the effectivness of Tacrine for treating dementia.  Some of the terms were identified using the MeSH browser function in OVID.