When to change paragraph in fiction

For fiction, you’ll construct your paragraphs for setups, punches, and other desired effects. For example, the one-word paragraph.

THE RULE: Always start a new paragraph when you switch speakers in dialog.
GUIDELINES: Start a new paragraph when

1.a new character reacts or does something,

2.a new character thinks something,

3.a new idea enters,

4.a new event happens,

5.a new setting occurs,

6.the reader needs a break from a long paragraph,

7.the “camera” moves. Ray Bradbury suggested, as in movies, every time the camera angle changes, start a new paragraph,

 8.a portion of information isn’t closely related to another and needs to be distanced,

9. a change in emphasis or tone is needed in a topic,

10.the time moves forward or backward,

11.a description of one thing ends and something else is described,

12.a special effect is needed to add humor or drama.

Source: http://zoemmccarthy.com/writing/13-guidelines-for-when-to-start-a-new-paragraph-in-your-story?subscribe=opted_out#blog_subscription-2