Search in databases such as ERIC or Education Source and Educational Administration Abstracts. 

Sample topic:  I am interested in exploring student retention at HBCUs.  Ideally I'd like to look at qualitative research articles.

Use Basic Search:

Only 10 articles on this topic in a key education database? The search needs to be modified to find more. 
 

Use Advanced Search:  It provides multiple search fields.  One strategy is to think about synonyms for each concept:

hbcu, hbi, "historically black colleges and universities"

retention, persistence, graduation, success

qualitative, narrative, "case study"
 

Advanced Search:     Use  or   between synonyms.  Use  "  "  around phrases.

Review what you've found.  Searching is iterative and can be nonlinear.
You can also Refine your search results.  See the left side of the display screen for LIMITS - Peer Reviewed, Publication Date and more.