The guidelines for quoting a person or a publication are detailed but straightforward. Here is a summary of basic procedures.
If a quoted word, phrase, sentence, or longer unit of text is described appositively (that is, if a descriptive word or phrase equivalent to the text it describes is immediately adjacent to that text), as in “Consider the saying ‘A stitch in time saves nine,’” note that no punctuation intervenes between the description (here, saying) and the saying itself.
However, if a simple attribution such as “Smith said” directly precedes a quotation, separate the attribution from the quotation with a comma: “Smith said, ‘A stitch in time saves nine.’” But if the attribution is an independent clause that sets the context for the quotation (as in “Smith had this to say about the issue: ‘A stitch in time saves nine’”), use a colon after the attribution, as shown.
When a seamless integration of the attribution and the quotation occurs, omit punctuation between them and do not capitalize the first word of the quotation (unless it is a proper noun), even if it began a sentence in its original spoken or written form: “The commission asserts that ‘as a general rule, the full board should have primary responsibility for risk oversight.’”
Reducing a full quotation to a partial one is also a good strategy when a speaker says something eloquent, pithy, or vivid but does so as part of a bland, convoluted, or ungrammatical statement. If the quotation is an incomplete sentence, or you want to isolate the effective part of the sentence, format the partial sentence as described above: “Smith said that he hoped to ‘knock some sense into people’ with his new program.” (Note that a paraphrase can follow as well as precede a partial quotation, with no intervening punctuation.) However, if it’s not necessary or desirable to use any of the source’s exact words, paraphrase the entire comment: “Smith said that he hoped to attract some attention to the issues with his new program.”
When the attribution occurs in the midst of a quotation, commas should precede and follow the quotation: “‘As a general rule,’ the commission asserts, ‘the full board should have primary responsibility for risk oversight.’” Note that—in American English, at least—the first comma always precedes the close quotation mark(s), because it is part of the quotation, but the second comma precedes the open quotation mark(s), because it is part of the attribution. (Exercise caution when inserting an attribution near the beginning of a quotation, however; doing so before any significant information is provided within the quotation is distracting—why prematurely identify the source of what is, so far, nearly devoid of context or meaning?)
Attribution often follows a quotation: “‘As a general rule, the full board should have primary responsibility for risk oversight,’ the commission asserts.”
If an attribution divides one full sentence from one or more other sentences, the first sentence should end with a comma (or a question mark, an exclamation point, a dash, or an ellipsis) preceding the close quotation marks, but a period should follow the attribution, and the remaining quoted content should begin with a capital letter: “‘As a general rule, the full board should have primary responsibility for risk oversight,’ the commission asserts. ‘However, other parties may be involved in monitoring risk.’” (Avoid delaying attribution in a quotation consisting of two or more full sentences beyond one sentence, and even consider inserting the attribution in the midst of a long, convoluted sentence so as not to excessively postpone its appearance.)
Use a question mark if the quotation is an interrogative or an exclamation point if the content of the quotation preceding the attribution merits that emphasis, employ a dash to indicate suddenly interrupted dialogue, or insert an ellipsis if the speaker deliberately leaves the statement unfinished.