No matter where you're searching, you will need to pick out the most important keywords. These are generally nouns.

How does a college education affect a retail manager's salary? The effect of a college education on a retail manager's salary.

Other related words might be:

KEYWORD	NARROW RELATED WORDS	BROADER RELATED WORDS
College education	Goshen College, degree	training, instruction, schooling
Retail	Macys, Kohls, sales, store, retailer	occupation, vocation, business
Manager	supervisor, managerial, management	profession, career
Salary	pension, wage, wages, paycheck, take-home pay	compensation, contract, money, payment

The list you make will help you search for your topic. Note that both narrow and broad related words are included. Include everything you can think of.