By now you should have determined the key terms from your PICO question and relevant synonyms. Read the tips below to see best determine how to search each database for those terms.
Boolean Operators
Get a refresher on how to use AND, OR, & NOT in your search strategy.
Subject vs. Keyword
Subject headings describe the content of each item in a database usually using a controlled vocabulary. Use these headings to find relevant items on the same topic. Searching by subject headings is the most precise way to search article databases.
It is not easy to guess which subject headings are used in a given database. Look for a link titled "headings" or "thesaurus" in each database to search for subject headings.
MeSH stands for Medical Subject Headings and are the subject headings used in PubMed.
Keyword searching is how you typically search web search engines. Think of important words or phrases and type them in to get results.
Here are some key points about each type of search:

Source
This video will show you how to search for your topic using the MeSH terms you identified previously.