These pointers are from Rootsweb:

Enclose a phrase or search string in quotation marks to find messages containing certain words in a certain order. The keyword(s) Worthington Hills Cemetery will find messages containing Worthington, or Hills, or Cemetery. Adding the BOOLEAN quotation marks to the search string, "Worthington Hills Cemetery", will return only messages in which that exact phrase appears.

A plus sign (+) in front of a word means that word must be in pages for them to be a match. For example, Obituary +Thompson will return only messages containing the word, obituary, that ALSO contain the word, Thompson.

A minus sign (-) in front of a word means that any page that has that word is excluded from the list of matches. For example, "Morgan County" -Roberts will return messages containing the phrase "Morgan County", that DO NOT contain the word, Roberts.