Always give credit when you quote from another writer's work, regardless of how little of the material you use. Give the name of the author, the work quoted and the publication where the work appeared. If you paraphrase an author's work, full credit is not necessary, but you should still reference the author you're paraphrasing. Examples of paraphrasing include restating something by rearranging the order of the words and adding fresh material or by stating in a general way what another author wrote (summing up another author's work). There are many different ways to give credit to sources. In most cases, refer to MLA or APA style guidelines (see Resources). In a work of fiction, it's acceptable to attribute quotes for song lyrics at the beginning of the book with the name of the song, the music publisher, the composer name and copyright information if different.
Keep quoted material proportional. Do not quote lengthy passages if you're using the material in a short story or article. If you're using an excessive amount of material from another writer's work, consider contacting the writer to secure permission. For instance, three or four paragraphs from a 500-page novel, used in the context of your writing and properly attributed, would be acceptable. The same number of paragraphs from a short story of 3,500 words would be excessive whether you gave attribution or not. There are no hard and fast rules about how much of someone else's work you can use; however, if the material you use by someone else is a major part of what you're writing, you've probably gone too far. No matter how small a portion of someone else's words you use, give proper attribution.
Always opt for originality. If you must quote, do so with the aforementioned steps in mind. But whenever possible, find a way to present an idea in your own words. Strive to add something original to the idea. If, for instance, your topic is working parents and their effect on children -- and the material you're researching says a higher rate of kids fail school when both parents work -- you can expand upon this idea by using personal experience or knowledge of the subject. You can restate the basic premise, but cite your source, even when everything you're writing is original.
Avoid copying and pasting from websites, a frequent practice these days. Most people unfortunately assume that information on the Internet is free because it's freely available, or that paying for Internet service gives them the right to use anything they can access. This is not the case. If you use anything from the Internet that is not public domain (and very little on the Internet is public domain) you are committing copyright violation. Anything you copy and paste needs to be quoted appropriately and in context, in small passages, and properly attributed. If you can't find the name of an author for work you're quoting, try e-mailing the website owner for permission. At the very least, cite the website as a source using the name of the article you're quoting from, the name and URL of the website, and the date you retrieved the material. For Instance, "The Making of Cold Storage." Writer's Inkwell (underline name of website), July 01, 2009, (insert URL).