There's a really useful article in Real Simple this month that I thought I'd share. Follow these four tips from Randolph Hock, author of The Extreme Searcher's Internet Handbook.
TO FIND: PDF's, Excel spreadsheets, or PowerPoint presentations
Use: filetype:pdf, filetype:xls, or filetype:ppt
Example: Canon manual filetype:pdf
Why: If you include the file type in your search, Google will turn up only relevant files. For example, entering filetype:pdf will find all the PDFs that have to do with operating your new camera.
TO FIND: narrowed-down information
Use: a hyphen (minus sign)
Example: jaguar -cars -football
Why: You want information about jaguars—the animal, not the car or the sports team. Placing a hyphen before terms you want to exclude will omit pages with those words. Type a space before the hyphen, not after.
TO FIND: a product you saw online (but can't remember where)
Example: intitle:"Frye boots"
Why: Using the term intitle: searches the words in the title bar of the Web pages and can be particularly helpful if you remember the name of the product you liked but not where you found it. Just be sure not to put a space after the colon and to use quotation marks around the phrase.
TO FIND: a verbatim phrase
Use: quotation marks
Example: "Bikram yoga"
Why: Using quotation marks around a phrase or a person's name can eliminate many of the irrelevant links you would otherwise turn up.