Do you allow your actors to own the words of a script without any intervention or do you sometimes change the way they speak the dialogue?
In terms of feature films, that’s a better question for the director, because ultimately it’s the director who guides the performance. But in times when I’ve been on set as a writer (such as GO), I try to step back and let the actor find the right way to get the words out.
When you tell an actor exactly how to say something, that’s called "giving a line reading," and it’s considered one of the biggest no-no’s, sure to raise the hackles of actors everywhere. But there are subtle ways to influence a line’s delivery without explaining it word for word.
For instance, an actor might be directed to "throw the line away," (play it as unimportant, even if it’s not), or "really let it sting." Another technique is to offer an alternative line that the actor can play in his head while saying the line written. For instance, "When you say, ‘It’s really nice to see you," let it mean ‘Go to Hell.’" The important thing is to let the actor find the means – the tone and inflection – while getting across the intended message.