Phrases: You can include phrases as well as individual words in your search. Your results will be more relevant if you use quotation marks around your phrase e.g. "study skills"
Abbreviations: If there is a well-known abbreviation, it may be helpful to try this when searching as well as the full form of the word or phrase
Plural: Using the plural may change your results e.g. woman or women
Alternative spellings: Try using alternative spellings where appropriate e.g. American variants or historical variants.