Let’s be honest. You can read your manuscript seventy times and still miss certain grammar mistakes. And if you’re like me, you’ll miss them all! 

In hopes of helping you out, I sat down with my editor, and we came up with 10 of the most common grammar mistakes spotted in fiction manuscripts. Sit back, sip a glass of something icy, and know that if any of these sound familiar, you’re in good company!

1. Using a comma with an action beat

❌ “I don’t know,” she shrugged.
✅ “I don’t know.” She shrugged.

This one can be confusing, but remember: shrugged isn’t a dialogue tag. You can say, ask, whisper, shout, and mutter words, but you can’t shrug them.

Compare:

✅ “I don’t know,” she said.
✅ “I don’t know.” She shrugged.

2. Capitalizing dialogue after a dialogue tag

❌ “Where are you going?” She asked.
✅ “Where are you going?” she asked.

Often I type this correctly, but auto-correct capitalizes the S because it follows a question mark. Just remember that even if dialogue ends with a question mark or exclamation point, the dialogue tag is still part of the same sentence.

3. Comma splices

A comma splice happens when you connect two complete sentences with only a comma.

❌ He opened the door, she was standing outside.
✅ He opened the door. She was standing outside.

Or:

✅ He opened the door, and she was standing outside.

This one can be sneaky, and sometimes proper grammar feels clunkier.

4. Misplacing the apostrophe in possessives

One character:

✅ The girl’s coat.

Multiple characters:

✅ The girls’ coats.

And then there are names ending in s, which can look awkward but are usually still written:

✅ James’s car
✅ Chris’s apartment

5. Mixing up lay and lie

Oh, I HATE this one! In fact, I often rewrite the sentence just so I can avoid the word. 

You lie down yourself.

You lay something down.

✅ She lies on the bed.
✅ She lay on the bed yesterday.
✅ She lays the book on the table.
✅ She laid the book there yesterday.

6. Dangling or misplaced modifiers

❌ Walking through the kitchen, the broken glass caught her attention.

Technically, this sentence is communicating that the broken glass was walking through the kitchen. Eeek!

Better:

✅ Walking through the kitchen, she noticed the broken glass.

Whenever you start a sentence with an action, make sure the person doing that action comes immediately afterward.

7. Accidentally changing tense

This happens a lot during revisions, especially if you aren’t always certain if you’re going to write the book in past or present tense.

❌ She walked into the room and sees him standing by the window.

✅ She walked into the room and saw him standing by the window.

If you’ve rewritten a paragraph multiple times, double-check the tenses. 

8. Confusing who and whom

The simplest trick I know:

If you could replace it with he/she, use who.

If you could replace it with him/her, use whom.

✅ Who called you?
He called you.

✅ Whom did you call?
I called him.

All that said, fiction dialogue should sound natural. If your character would never say whom, don’t have them sounding like a Victorian headmaster just to satisfy a grammar rule.

9. Putting punctuation outside quotation marks

In American English, commas and periods almost always go inside quotation marks.

❌ She called him “impossible”.
✅ She called him “impossible.”

And:

❌ “I’m leaving”, she said.
✅ “I’m leaving,” she said.

10. Unclear pronouns

This typically happens when a sentence includes two people of the same gender, and it’s not obvious which person ‘he’ or ‘she’ refers to.

❌ Sarah handed Megan the letter after she sat down.

Who sat down, Sarah or Megan?

Better:

✅ After Megan sat down, Sarah handed her the letter.

Or:

✅ Sarah sat down, then handed Megan the letter.

I run into this often in scenes that have two women or two men interacting. If you have to reread the sentence to figure out who a pronoun belongs to, your reader probably will too.

Of course, grammar rules aren’t the boss of your novel.

Dialogue can be fragmented. 
Sentences can be incomplete. 
You can start sentences with And. 
You can intentionally break rules for voice, rhythm, and effect.

The important thing is knowing when you’re breaking a rule on purpose versus when a mistake has tiptoed past you.

Happy writing (and editing),

Alessandra