I've been starting a new paragraph whenever there's been more than the slightest tick between speeches; however I'm not sure this is always the best way to do things. An example (made up to illustrate, not from my work) 1. "We could go down the shops," Mary said. "I need some new shoes." - Definitely no new paragraph 2. "We could go down the shops," Mary said. She picked up one leg and rubbed at her ankle briskly. "I need some new shoes." - I'm thinking still no new paragraph, because it's a continuation of the same idea. 3a. "We could go down the shops," Mary said. She stooped down, spotting something on the verge. A four leaf clover. She pocketed it, then turned back to Ethel. "I need some new shoes." - While Mary carries on speaking without anyone else doing so, the interruption to the speech is a different idea to the original therefore causes a paragraph break. It reads better for me than: 3b. "We could go down the shops," Mary said. She stooped down, spotting something on the verge. A four leaf clover. She pocketed it, then turned back to Ethel. "I need some new shoes." But is there a right/wrong or particularly preferred way of handling this? What's your preference?
I would say that you should format the text so that the speech is easy to follow. If this means new lines then new lines it is. One rule I do know of is that there should be a new paragraph/line every time the speaker changes.
Use 3b rather than 3a. If you put speech in a new paragraph, your reader will assume the speaker has changed. For the reader to understand the speaker is still Mary, keep "I need some new shoes" in the same paragraph. There is, of course, an exception. If the speaker is giving a long speech that has paragraph breaks in it, you finish a spoken paragraph without closing the quotes, and begin the new spoken paragraph by opening quotes, like this: "We could go down to the shops," Mary said. "I need some new shoes. All my old ones are, well, old, and some of them are falling apart already. I lost a heel yesterday and I'd rather spend money on new shoes than on repairing old ones. "Jane and Alex's wedding is coming up in two weeks, too. That's as good an excuse as any." 1 and 2 are correct as written.
