A recent - or older, interesting, classic - book on your topic is a great start. These can be found by browsing the book collection (see Call Numbers) or using the Library Catalog (see Subject Headings). Or perhaps someone recommends a title "you must read." Or you might start with one of the many reference books with their lengthy bibliographies, or with the bibliography in one of your textbooks, or with a title recommended by your instructor.
Note that the HSU Library has extensive collections of materials related to American Indians
E51-73 Pre-Columbian America
E77 General works
E78 By state, province or region, A-Z
E98 By subject, A-Z
E99 By Tribe, A-Z
Library of Congress Subject Headings
Indian art North America
Indians of North America - Fishing
Indians of North America - Education
Indians of North America - California - Education
Navajo Indians - Education
Education - California
United States - Civilization - Indian influences
See also the ANSS Cataloging Questions & Answers for tips on subject searching and the AILA Subject Access and Classification Committee Wiki to keep up with changes and hot topics in subject heading work.