1. START EARLY. Think about the timeline for your assignment and what is logistically possible in terms of research. Not everything is readily available online, and many of the students in your class may be writing on a similar topic. If most of the books you want to use are already checked out, you may need to rely more on scholarly articles instead.
2. CONSIDER A VARIETY OF WAYS TO SEARCH FOR YOUR TOPIC. For instance, if you are interested in Technicolor, you can search by that particular word. But, also consider looking up content on the history of cinematography, Kodak, color motion pictures, specific films as good examples, and the names of individuals associated with its development.
3. BE WARY OF TOPICS THAT ARE TOO BROAD. If there's an entire book written on your topic (for example "women in early film" or the Depression), that's a good sign you need to find a more specific way to write about the subject. For instance, perhaps there is a specific person, court case, issue, studio, film, etc. that can be your primary focus within the larger context. However, an overly narrow topic on which very little of substance is written can also require you to rethink the focus of a paper. Many topics don't have an entire book written about them, so it's often a good idea to start with general histories of the early industry with chapters that cover your time period/subject.
4. USE CARE WHEN MAKING GENERAL ASSUMPTIONS ABOUT AUDIENCES AND CULTURAL NORMS. Many of the readily available primary resources from the early 20th century are written in mainstream American newspapers and entertainment industry magazines. While these publications do have differences in focus and presumed audiences, they represent one subset of critical and popular opinion. If a film or movie star is reviewed a certain way in these sources, it does not therefore follow that "everyone" or "most of the American public" necessarily thought the same way.
5. ASK FOR HELP IF YOU NEED IT. Historical research can be challenging, especially if your topic is more complicated or the most obvious materials are checked out. Ask for help from a reference librarian if you need more guidance or have a question about conducting research. Talk to your T.A. about refining your paper topic, your thesis, and expectations of the assignment. UCLA also has a Writing Center to assist you.