The best way to find a librarian who might be able to help you with your particular topic is to think about institutions (colleges and universities, museums, or public libraries) that have relevant information. If your topic has a geographic link, you can try librarians in that specific place. Below you'll find more tips to find helpful librarians!
Library Websites!
National: Library of Congress (LOC) Ask a Librarian - Use Chat Service!
Local: Ask a Librarian at San Francisco Public Library
Most local: Sarah Levin and Jo de Pirul @ LibraryDept@urbanschool.org
Archives Galore:
Go to “Contact Us” at Digital Feminist Archives at Barnard Center for Research on Women
List of Women’s Archives in the U.S. - look and contact their librarian(s)!
Smithsonian Institute Archives for Researchers - many primary sources & artifacts!
Online Archives at the GLBT Historical Society - SF Local!