* When there is a significant change in the scene or setting. For example, if the characters move from one room to another, or if the time of day changes, you may want to start a new paragraph.
* When there is a change in the tone or mood of the conversation. For example, if the characters start arguing or if someone makes a joke, you may want to start a new paragraph.
In general, it is best to start a new paragraph in dialogue whenever there is a significant change in the conversation. This will help to make the dialogue easy to read and follow.