You must be absolutely certain about details when you use quotes, whether the source is a person you interviewed or a written quote that you uncovered during your research. Because quotes are assumed to be exact, you need to ensure that all the details you have in your notes are precise as well.
You can check quotes you gleaned from written sources by referring back to those same sources. You can check quotes that came directly from a person you interviewed or one you asked for information if you have a tape recording of your conversation.
If you don't have a tape recording, you should be absolutely sure you that wrote down the person's responses word for word. If you are at all unsure, double-check with the person you are quoting.
All direct quotes must be enclosed in quotation marks. Place the quotation marks around the exact quote itself, which may be only part of a sentence if the rest is in your own words. Always immediately attribute the quote to the person who said it.
The wording of a quote must be exact. You cannot paraphrase any part of what was said and then pass it off as the words of others. You also cannot make any improvements to the quote if you think it could be worded better. If you feel it needs this, you can write your own explanation or clarification, but make sure you differentiate between the quote and your wording.
Keep your notes and tape recordings of any interviews you have conducted. Interviewees can dispute that they ever said what you recorded as a quote in your paper. If you have a tape recording as a backup, you can prove that you did in fact use an exact quote.
Make sure that you attribute any quotes to the people who said them. This may seem obvious, but is the cause of many errors. If you are talking to one person, it is very clear who should be quoted. But, if you are talking to a group of people, you need to make sure you know exactly who said what. Don't rely on your memory; write down who is responsible for each quote.
If you are getting a quote from a book, it may be unclear who should be credited with the quote. Make sure you understand without a doubt who it was. If you can't be sure of who said it, don't use it as a quote at all. You can still use the information that comes from the quote, but instead put it in your own words.