Don't interrupt the flow of text. Magazines have been using quotes, highlights, and other text breakers for years. Any interruption of text causes the reader to stop reading. I have found no evidence of this in the many focus groups I have observed or in The Poynter Institute's own EYE-TRAC Research. So length of the interruption and its placement determine legibility factors.
Readers prefer justified type over ragged-right type.
This, too, is only in the minds of editors and some designers. There is no evidence of the truth to this perception. If newspapers had always set all their text ragged right, readers would have accepted that style. Ragged-right type can change the rhythm on the page, even when used for short texts or for columnists. Its use incorporates white space, which is always needed, and allows for more appropriate letter spacing within and between words.