Before you begin your research, write out a few detailed sentences about your topic. Underline the main words in these sentences. From the description that you wrote, create a list of related words and phrases.
Once you have an initial list, think of other terms that also describe your topic. Write down any ideas you have, even the ones that seem harebrained; sometimes they end up being the most helpful.
Come up with synonyms - other words or phrases that have the same meaning - for your terms. Don't forget to list alternative spellings, abbreviations, and acronyms for words on your list. You should also identify words that have broader or narrower meanings than your original terms.
The words and phrases you come up with can then be used as keywords in your searches.