Marie desJardins suggests, "When you first start reading up on a new field, ask your advisor or a fellow student what the most useful journals and conference proceedings are in your field, and ask for a list of seminal or 'classic' papers that you should definitely read."
In addition to discussions with your advisor and strategies such as following your interests and searching the important article databases in your discipline as well as the UCLA Library Catalog, other suggestions include:
DesJardins also suggests that you start a journal of your research activities and ideas, keep files of the papers you read, and create an an online bibliography.
Researching a dissertation topic includes checking to see of someone has already written on the topic you are considering. These sources can be consulted as part of your search. Dissertations not owned by UCLA may be requested on interlibrary loan from other institutions.
UC's open access repository. Contains books, journals, working papers, conference publications, postprints, theses, and dissertations.