Bibliographies are everywhere
Every time you find a relevant resource, check the bibliography and notes. For example, the works cited at the end of encyclopedia articles are short but are usually selected for authority and quality. Similarly, recommended reading lists and bibliographies in textbooks are helpful introductions to the literature of the discipline. Thus the works cited in all kinds of resources can lead you to more relevant material. Keep an eye out for leads.
Coverage
Some bibliographies are comprehensive and collect all material published on a certain subject between specified dates. Other bibliographies are selective and only list what they consider to be the best or most useful sources. It is a good idea to scan the introductory material in bibliographies (this would include preface, introduction, user's guide, etc.) for information about inclusion criteria, dates covered etc.
Currency
Consider the date the bibliography was published. Research with a bibliography usually has to be supplemented by searching a library catalogue or index to find the most current material. In addition, check the works cited by journal articles and theses on your topic, as these are likely to include the most current material the authors could find.
Intellectual organization
The organization of a bibliography can be very useful for increasing the understanding of the subject. The schema and categories used by longer bibliographies can provide an overview of the structure of the subject and indicate helpful ways a subject can be broken down.
Excellent for historical research
Bibliographies are particularly important for historical research as they often include older and less common sources not likely to be found using online databases. This also highlights one of the limits of bibliographies: They are not so helpful for research on very current topics.
Use with your local library
Bibliographies should be used in conjunction with the catalogue at a local library. Someone has put together a list of material, you just have to try to locate the items. Bibliographies will probably contain references to sources not available in your library. Interlibrary loan service should be used at this point (if you have time to wait for the books and articles to arrive).
Research tip: "After a while, you should start recognizing some items in a new bibliography as things you have already read or seen listed elsewhere. When that happens, you're getting a handle on the literature of the subject. If you have been reading for several weeks and aren't beginning to notice this kind of closure, perhaps you should place some additional limitations on your topic." (Whiteley 1994, 6).