To determine which database to use ask yourself the following questions:
For example, if you are conducting research for an annotated bibliography in Freshman Year Experience you might search the Academic Search Complete database because it is multidisciplinary and covers a wide range of subjects. Or you may choose Discover to search multiple databases at one time! Take a look at the "Finding Library Materials" tab to view the tutorial on how to search Discover if this is your choice.
On the contrary, if you are looking for primary research in the Nursing field, you may want to look at the Nursing Subject Guide and select the Nursing & Allied Health database.