The advent of the Internet has made plagiarism and uncredited research increasingly common. Properly crediting and citing the words of others tells your readers that you are both a careful researcher and an honest writer, setting you apart from the crowd and making you a respected information source.
Ask what the preferred citation format is for the paper's audience. The formats most commonly used are the MLA for the humanities, and the APA in the social sciences; some academic fields, such as law and sociology, have their own, specific requirements. Find a copy of the appropriate style manual (or use Purdue University's Online Writing Lab for MLA, APA or Chicago Manual of Style) to reference, as there are as many formats as there are sources.
Note the information needed to cite the source of the quote. If the source was a book, you will need the book's title, publication date, author or editors, and the page where the quote is located. A published interview requires similar information for a magazine article: the publication title, the title of the interview, the interviewer's name, publication date, and the page(s) where the interview appears. Citations for personal interviews generally only require the name of the interviewee and the date.
Investigate the relevant credentials of the quoted person. Everyone has some credentials to their credit, but a Ph.D. in philosophy is not relevant when quoting someone on car repair. From the relevant credentials, choose the one that will inspire the most confidence in your audience.
Tailor the quote to fit seamlessly into your paper, by knowing its purpose and whittling the words down to the necessary ones. Use square brackets to indicate any grammatically necessary changes to the quote, and ellipses to indicate any words omitted.
Enclose the quote in quotation marks. End the quote with a comma, inside the quotation marks if writing for an American audience, and outside otherwise. After the closing quotation mark, write "says" followed by the person's name and his most important credential. Read the sentence aloud to proofread. Make sure that the quotation marks are the only way to tell where the quote begins and ends.
Add the proper in-text citation for your quote. Follow the required citation format for your essay when including the source on your works cited page.