Most of your quotes will be explanatory , meaning they are fleshing out a paraphrase and would make little sense without some additional explanation. When you interview witnesses for a story, they will most commonly give you explanatory quotes. Do NOT quote, then explain. Quotes must always be attributed, and usually within the same sentence. If it is clear from an earlier sentence in the same graph who is speaking, then you can use a pronoun or an elaboration.
Expository quotes tend to come from professional spokespersons.
This usually means a public relations practitioner or someone who is very used to speaking before an audience, such as politician. These quotes tend to be very well-organized, because the speak is not making the comment extemporaneously. She knows exactly what she will say long before she says it. Such quotes generally can stand alone, in that they need no introductory paraphrase in order to make sense.