I like to use the same techniques as developing a topic sentence, for developing a search strategy.
Start with your topic sentence. I am researching adolescent healthy eating initiatives.
Next break it down. What are other words that can be used?
adolescent young adult teen* picks up teen, teens, teenager, teenagers
healthy eating nutrition
initiatives programs projects studies
Connect them using the following words
and : narrows your results. All words must be in the results adolescent and healthy eating
or : broadens your results. Any of the words must be in your results. healthy eating or nutrition
not : excludes words. adolescent not (males or boys)
() : allows you to combine it all together. (adolescent or teen* or young adult) and (healthy eating or nutrition) and (initiative or program or study or projects)