Getting Started: How do I find Census Records?
The census are organized by island, then by district. The first thing you want to do is generate a list of your kūpuna that you think would be alive during a certain census, then think of where they would be located. For the early censuses (before 1900), you will need to manually search through each census: page by page, line by line, family by family on microfilm. For the later censuses (after 1900), you can actually do a keyword search for your kūpuna online.
The microfilms for the early censuses (before 1900) are located at Hamilton Library, the Hawaiʻi State Archives, Hawaiʻi State Library Main Branch.
The later censuses (after 1900) are located online in a family genealogy database through the Hawaii State Library. You will need to have a library card to access the database.