Unfortunately, typing a question into a library database (or into Google for that matter) is not the most effective way to search. Before beginning any search, you should break your research question into main ideas. Then, brainstorm synonyms and related terms that could be used to express these ideas.

For example, if I was wondering what impact globalization has had on tourism in Latin America, I might start by selecting the following keywords:

My next step would be to think of other ways to express these ideas, as well as thinking about possible related terms that I may need to add to my search. (Related terms are listed in the same columns in the table below).

A good strategy is to begin with just a few keywords; this results in a broader search, which you can then refine.