To get more specific search results, try using the following tips:

Check spelling
Make sure your search terms are spelled correctly. The search engine will attempt to find words that sound similar your search terms, but it is always best to try to spell the search terms correctly.

Use multiple words
Use multiple words when performing your search. The search results will return more refined results from several words than from a single word. For example, typing our free service will yield more relevant results than typing only service. (Keep in mind, relevant results are returned even if they don't contain all query terms.)

Use similar words
The more similar words you use in a search, the more relevant results you will get back.
Example: safe secure privacy security

Use appropriate capitalization
Capitalize proper nouns. Lowercase words will match any case. For example, typing search will return all documents containing the words search, Search, and SEARCH. However, typing Search will only return pages containing Search with an uppercase S.

Use quotation marks
Use quotation marks to find words which must appear adjacent to each other, for example, "our pledge to you." Otherwise, the search results will include the words our, pledge, to and the word you, but not necessarily in that order. The words may appear anywhere, and in any order, within the document.

Use plus (+) or minus (-)
Use a plus sign when your search term or phrase must appear in the search results. Use a minus sign to indicate undesirable term(s). The plus sign tells the search engine that a certain word or phrase is required in the search results, and a minus sign indicates that a word or phrase must be absent in the search results.

Note: A phrase must be contained within quotation marks. Leave no spaces between the plus or minus sign and the term.

Use field searches
Field searches allow you to create specific searches for words that appear in a specific part of a document. A field search can be performed on body text (body:), title text (title:), alt text (alt:), meta description (desc:), meta key words (keys:) or URL (url:). The field name should be in lowercase and immediately followed by a colon. There should be no spaces between the colon and the search term.

Note: The field searches can only be followed by a word or phrase. Phrases must be contained within quotation marks.

Use wildcards
Wildcard searches can expand the number of matches for a particular request. The * character is used as the wildcard character.
For instance, searching for wh* will find the words what, why, when, whether, and any other word that starts with wh.
Searching for *her* will find the words here, whether, together, gathering, and any other word that contains her anywhere in the word.

Wildcards may be combined with the standard plus (+) and minus (-) modifiers, quotes for phrases, as well as the field search specifiers.
+wh* -se*ch will find all pages which have a word that starts with wh and which does not contain a word that starts with se and ends with ch.
"wh* are" will find the phrases where are, what are, why are, etc.