An easy way to start your search is the find one or two relevant articles and use these to see what keywords you might use to find others like them.
You can also look to see how these articles are indexed. To do this, search for one of the articles by title in the database you wish to search. View the full record to see what subject headings have been assigned and add these subject headings to your search.
Librarians call this "pearl growing".
Tip for building your Medline search:
In Google Scholar, view all versions of the relevant article you have found and view the version that has the link "ncbi.nlm.nih.gov". This will bring you to Pubmed, where you can click on "MeSH terms" to see what subject headings were used in Medline.