1) Use Wildcards
eg: wh* will find the words what,why,when,whether and any other word that starts with wh.
eg: wh* are will find the phrases where are, what are, why are.
Wildcards may be combined with the standard plus(+) and minus(-) modifiers,quotes for phrases as well as the field search specifiers.
eg: +wh* -se*ch will find all pages which have a word that starts with wh and which doesn't contain a word that starts with se and ends with ch.
2) check spelling
The search engine will have to find the words that sound similar to the search term. The search engine have to check the spelling of the search term.
3) Use quotation marks
find the words that must appear adjacent to each other.
eg: "our pledge to you" have to find the words adjacent to each other but not the word our, pledge, to, you somewhere in someorder.
4) Use plus(+) or minus (-)
plus(+) to indicate the desirable term in the search result.
minus(-) to indicate the undesirable term in the search result.