Use keywords to make a concise search query and avoid full sentences or too many words - this will yield better results :).
For example, Mexican Americans and activism.
Combine the name of the group you are studying with the aspect you want to find out about. For example,
Chican* AND (combine with one of the following):
Note: using the asterisk (shift 8), like in the example above, is called truncation. For example, Chican* will search for Chicana, Chicanas, Chicano, Chicanos, Chicanx, Chicanismo, Chicanidad, etc.