Pick up your cues.

We can talk about punctuation as a clue to the character. That works sometimes, and other times it can make everyone extremely self-conscious about the text, and too many pauses and all that.

If you really want a physical experience of the rhythm of the text in DIALOGUE the most important thing is: pick up your cues. Then you'll begin uncovering the pattern. Sentence length. Line length, I guess you could call it. But it's really sentence length, how the speech goes back and forth between people.

Let's see: a summation:

Pick up your cues.
Pay attention to sentence length in relation to surrounding sentences. In other words, become aware of the PATTERN of the length of thought.
Know the difference between ponderous speech and "back and forth" or "repartee"

In a SPEECH you want to pay a lot of attention to punctuation and sentence length to begin to figure out the pattern of back and forth within the speech.