Here are the foundational steps and tips to follow when conducting library-based research. The following are steps. They don't have to follow each other. Depending on where you are in your research work, you can jump in and use what you need.
Hispanic Americans: A Historical Sourcebook 2005 E 184 .S75 H54
The Hispanic Databook: Detailed Statistics and Rankings on the Hispanic Population, Including 23 Ethnic Backgrounds from Argentinian to Venezuelan, for 1,266 U.S. Counties and Cities 2004 E 184 .S75 H567 2004