Thomas Mann, (a reference librarian at the Library of Congress, not the dead German writer), has written several editions now of The Oxford Guide to Library Research. Mann has also taught classes at the Library of Congress for many years, to researchers new to the institution.
Mann's 12-step program is fascinating (to us librarians anyway!), but more important, it's very useful. His basic premise is - there is always more than one way to get what you need. You should get used to using as many of his strategies as you can, because where one falls short, another one succeeds.
- Browsing the stacks? Great IF the stacks are open, and if all the books are actually there. Find things you never thought to look for!
- Keyword searching? A good strategy to find a needle in a haystack, and to begin your research.
- Ask a human being? Sometimes the quickest way to your answer.
- Bibliographies? Do they still make those? Yes! And they can be a terrific starting point.
- Library of Congress Subject Headings? Whaaa? If you don't know about these gems, ask a librarian. Mann is a BIG proponent.
- Citation and related records searches? A really cool way to find stuff you can't find with any other search. Use the Web of Science for this.