You might start with a single word topic like GMOs or a question like "Should GMOs be sold for human consumption?" Before looking for answers, think about language. Make a list of keywords. Separate the different concepts in your topic.
Then enter these terms in the database's Advanced Search using the multiple boxes for the different key concepts in your topic.
Use * for alternate word endings
e.g., sustainab* retrieves sustainable, sustainability etc.
Use the different search lines to enter key words (not sentences) describing the different components of your search topic
Redo your search using new keywords you find in article titles, abstracts, and subject terms given to the articles by the database
Use or between synonyms or alternate concepts
e.g., greenhouse gas* or ghg* or carbon dioxide
Use fewer search terms.
Each time you put in another search term (unless they are synonyms combined with or) you will get fewer results.
Start with a small number of keywords and then add more terms or try different terms based on your results.
Use quotation marks around words you want searched as a phrase
e.g., "greenhouse gases"
Databases usually offer ways to Limit or Refine your search results, such as:
To Scholarly/Peer-reviewed journals
By publication date range
To journal articles only (or books, dissertations, etc)
Some databases also have specific limits or search options such as:
Methodology
Age Groups
Gender
Human/Animal
Add more search terms:
Each time you put in another search term, you will retrieve fewer results.
Start with a small number of keywords and then add more terms or try different terms based on your results.
Use the different search lines to enter more key words (not sentences) describing different components of your topic
In articles that look good, look for other terms in the title, abstract, and subjects.
Is it a primary research article?
Is it a review article, leading you to primary research articles?
Is it relevant to your specific topic, give you useful background information, or use a methodology you could use or adapt to your project?
Does publication date matter? If so, is it in an appropriate date range?
etc.