Whenever possible, use a thesaurus to help you with terms for your search strategy. Thesauri contain subject headings, controlled vocabulary or a standard way of representing a topic or concept. By using subject headings, you don't have to think of all the synonyms for a topic as you would with keyword searches (assuming you want to do a comprehensive search).
The thesaurus for the 3 American Psychological Association databases available via EBSCOHost (PsycINFO, PsycARTICLES, and PsycCRITIQUES) gives all the acceptable subject headings. Also included are related terms, narrower terms and broader terms asa well as the year the term was introduced. Subject headings will also have a scope note which defines the term, as well as indicatin for what the term is used for. For example:
While you might find some articles with the terms "financial stress," you'd be more successful using the subject "financial strain."
The thesaurus for PubMed is called MeSH (Medical Subject Headings) and it is available in the MeSH database via the National Library of Medicine. When you enter terms, you will find subject headings, subheadings and a search building tool:
Look intense? Don't be put off by this. When you search PubMed and just type in keywords, it takes those keywords and maps them against the thesaurus for you, as well as searches them in all fields. There are also Youtube videos if you want a live demonstration. Here's the one for MeSH subject headings.