The one grammar problem I see most frequently when I teach creative writing is with dialogue punctuation. And it’s understandable why this topic leaves many writers mystified. Dialogue punctuation is confusing. Is it a comma or a period before the end-quote? What if you have a question mark or an exclamation point? Here’s a quick run-down on dialogue punctuation.
A line of dialogue plus a tag is one full sentence, so you use a comma before the end-quote and before the tag.
“My name is Susan,” she said.
If the spoken part is followed by another full sentence, then you put a period before the end-quote and begin the new sentence with a capital letter.
“My name is Susan.” She extended her right hand.
Sometimes you have both a tag and a stage direction together. In that case, the stage direction is usually a subordinate clause so it’s still part of the same sentence as the spoken part.
“My name is Susan,” she said, extending her right hand.
Question marks and exclamation points are tricky because they can behave either like commas or periods depending on the situation.
“What’s your name?” she asked.
“What’s your name?” She leaned in to hear the answer.
“What’s your name?” she asked, leaning in to hear the answer.
“Somebody help me!” she screamed.
“Somebody help me!” She collapsed from exhaustion.
“Somebody help me!” she screamed before collapsing from exhaustion.