A concept cloud can be very useful in helping you generate keywords for your search strategy.
After coming up with the keywords, don't type too many words into the search box, and check your spelling when using OneSearch.
Not so great search: Should American football officials be held responsible for NFL players neurological health issues in retirement? -- this returns zero articles or books.
Go with simple search terms: NFL and concussions returns over 12,000 articles and books!