Always think about different ways to say the same thing.
Start with keywords to describe your topic, within results, look at the abstract and subject headings to identify additional keywords to use.
Quotes around a phrase
* at the end of the word to retrieve all the variations (or the middle for spelling variants)
outdoor* = outdoor or outdoors
garden* = garden or gardens or gardening
environment* = environment or environmental or environmentally
gr*ywater = graywater or greywater
combine word/s using connectors.
or: either term/s are included (to connect synonyms or like concepts)
economics or marketing
policy or policies
stormwater or rainwater or "storm water" or "rain water"
and: all terms must be included (to connect concepts)
"public health" and communication
gr*ywater* and parks
"community garden*" and regulation*
health and benefit*