Put your clinical question into the PICO format:
Brainstorm and jot down keywords for each part of your question. Try to think of every possible way an author/researcher might refer to your topics. Cross out words that aren't working and add to this list as you search.
Keep a search log or print your search histories. This will keep you from re-running the same searches and help you track how you've had to adjust your search.
This 4-minute tutorial explains how to use Boolean operators (AND, OR, and NOT) to build a search statement. (Click the button in the bottom right to expand the tutorial to full screen.)
Use an asterisk (*) after the root of a word to search for variant endings. For example, stretch* will find stretching, stretch, stretches, etc. This is called truncation.
Use quotation marks to keep words together as a phrase (e.g. "heart attack").
Look at the "help" menu in each database for more searching tips.
The American Occupational Therapy Association (AOTA) defines 5 levels of evidence when appraising research studies for evidence-based practice. The AOTA's EBP Project created the Guidelines to Critically Appraised Paper (CAP) Worksheet which provides the Levels of Evidence table and descriptions of the various study designs at each level.
You want to be certain to search in the relevant databases for your topic and for the level of evidence you need. Look at the descriptions of each database in this guide to decide databases which will help you find the type of articles you need. Be thorough by searching in more than one database.
Note: Don't be surprised or discouraged if you don't find higher levels of evidence on your topic. This can be a result of the newness of the particular topic and how much attention the research community has given to the topic.
With a project such as the Critically Appraised Topics (CAT) assignment which involves comprehensive literature searches, it may be helpful to understand the difference between keywords and subject headings and the differences when searching with each.
I recommend that you try both types of searches. Start with keywords, notice the subject terms found in relevant results, and then use these subject terms to set up more focused searches. There is no one-way to search; it is an iterative process, whereby you try one search, make discoveries which will further direct the next search, and so-on. Some searches may be all keywords, some all subject terms, and some a combination of both. Here's an example of a search in PubMed, that uses a Medical Subject Heading and a keyword phrase:
Child Development Disorders, Pervasive[MeSH] AND "therapy ball chairs"
When you can't find any or enough information or when the studies you're finding are of lower-than-ideal quality, try some of these tricks for broadening your search:
When you are getting large numbers of results, try some of these tricks for narrowing your search: