By creating a list of keywords, you will be able to build better and more efficient searches. Good keywords will return a smaller of number results that are more relevant.
1. Note single words or short phrases.
2. Play with synonyms
For example, start with the word "trash," then try using the words "garbage" or “waste.”
3. Think of related terms to describe your topic.
For example, related terms to "pollution" are "acid rain," "global warming," or "refuse water." The related terms may be more specific or less specific than your original term.