The first step to identifying keywords (search terms) is having an initial topic or research question to work with. Not there yet? Spend five minutes choosing a focused topic, then come back here.
Ready?
Step 1. Write down your research topic.
Example:

Step 2. Circle or highlight the most important individual ideas that make up your topic.
Hint: Look for the nouns.
Example:

Hint: Avoid these keywords, and why:
- impacting, effectively, address, effect - don't use these words in your initial searches about a topic. Adjectives and words that indicate a relationship between two ideas will greatly reduce the number of search results you get. That isn't helpful right at the beginning of doing research. If you retrieve lots of search results, then feel free to add these types of words into your search queries.
- pro, con, for, against - rather than using words that convey opinions about topics, use nouns that help you learn about your topic(s) from every angle. Examples of more inclusive nouns include outcomes, impacts, or results.
- it, to, and, of, about - these are "filler words" that search engines and databases ignore anyway.
Step 3. Brainstorm related terms and synonyms.
Hint: Think about words or phrases that have similar meanings to each idea, or that are closely related to the overall topic.
Example:

How to identify related terms and synonyms:
- Look online with a search like other ways to say _____.
- Search with your main idea. Skim the results and see how that idea is talked about or referred to by others.
- Pop your whole research question into your favorite search engine. Skim the results and see what related issues and ideas show up.
Synonyms need to make contextual sense:
- Synonyms are words that mean the same thing. But synonyms won't always make sense in the context of your topic.
- Example: Climate crisis.
- Emergency is a synonym of crisis. "Climate emergency" makes sense in the context of this research topic.
- Pickle is a synonym of crisis. "Climate pickle" sort of makes sense, but researchers, environmentalists, and authors don't use this term.
DONE! You've identified keywords.
Now you can apply basic search strategies to those keywords.