(with help from a Tumblr text post)

(1) Use commas instead of periods during the dialogue of your story (2) unless you are following the dialogue with an action and not a dialogue tag.

(1) "I like potatoes," he said politely.

(2) "I don't like potatoes." She sighed and went back to her story.

(3) It is appropriate to use a comma if there is action in the middle of a sentence.

(3) "Actually," he added, pointing to a carrot, "I like carrots as well."

(4) You can also end with a period if you include an action between two separate statements.

(4) "Yeah." She nodded. "I also like carrots."