Searching for literature is an iterative process. It is rare that the first search you put together will be your first and only attempt. You will want to revise and refine your search as you go along. Always keep your research topic and inclusion and exclusion criteria in mind as you refine the search.
After breaking your search out into concepts you will want to think about keywords to include.
Keywords, synonyms, and related terms are all helpful. Try thinking about how a concept would be described in the literature.
For example, it is rare that academic literature would use the term "baby" instead one could use: infant, newborn, pediatric.
When thinking of keywords try writing them underneath your major concepts, this will help you keep everything organized and straightforward. It will also help you craft a boolean search with consistent internal logic.
Along with Boolean Logic you can also use punctuation and truncation to craft an efficient and effective search strategy.
Punctuation: use quotation marks " " around words to search them as a phrase. For example, search for "rheumatoid arthritis" with quotation marks and most databases will search for it as a phrase instead of two distinct search terms.
Truncation: in many databases the truncation symbol is the asterix * . Put an asterix in word like prevent* and it will search for prevent, prevents, prevention, preventing etc.. It is an easy way to find many forms of a word without typing in all the keywords yourself.
Example: residen* finds: resident, residents, residency
In most academic databases (except GoogleScholar) you combine keywords using "Boolean Logic." Boolean Logic is the process of using AND, OR, or NOT to combine search terms into search strategies. An easy way to think about Boolean Logic is that AND narrows your search, OR broadens your search, and NOT excludes results.
Sample Question: Are there studies on education for residents or medical students about ebola?
Sample Search: ("medical education" OR "curriculum") AND (residen* OR "medical student") AND (ebola OR "ebola hemorrhagic fever" OR "ebola fever")
Use AND when you want the search to find all of those words in the results. For example, searching for genetic AND engineering will find only results that have both of those words in it.
Use OR to find any or all of your terms in the results. For example, searching for genetic OR engineering will find results that include only the terms genetic, only the terms engineering, and both genetic and engineering,
Use NOT to exclude terms from your results. Use this sparingly, in particular if you are looking for a specific population because if you want to find a study that includes men if you NOT women than it will exclude studies that have both genders included in the sample. This can remove articles that may be useful.
If you wanted to find articles that included the term genetic but not engineering you would search for genetic NOT engineering.
Here is a printable handout that explains Boolean Operators