Here’s Neil Cross, talking about dialogue:
… there isn’t much point in listening to what people say, because what people say isn’t usually all that interesting. It’s critically important, however, for any writer to spend as much time as possible listening to how people speak.
Which is a very different thing. It’s a distinction you have to appreciate if you want to spend your professional life putting words into the mouths of imaginary people.
To write good dialogue you don’t need to carry a notepad and pencil, and you don’t need a ‘good ear’ for what people say. You need to hear what people mean, which often means you need to hear what they’re not saying. Then you have to work out how to make your readers hear it, too.
Read the full piece here.