Add commas after "first", "second", "third", etc. when introducing a series of items. But a comma is generally unnecessary (and sometimes incorrect) when using "first" as an adverb of time, an adjective, or a noun.

Add commas after "first", "second", "third", etc. when introducing a series of items.

This is how to become a millionaire: first, stay out of debt; second, make savings a priority; third, work hard.

This is how to become a millionaire: first stay out of debt; second make savings a priority; third work hard.

But a comma is generally unnecessary (and sometimes incorrect) when using "first" as an adverb of time, an adjective, or a noun.

First go to a University; then get a great job.

Russia would be first on a list of the largest countries by surface area.

1. When to Place A Comma After 'First', 'Second', 'Third', etc.

Include a comma after "first", "second", "third", and so forth when introducing a list of items.

Three quick tips for successful exam preparation: first, give yourself enough time to study; second, use flow charts and diagrams; third, practice on old exams.

Recommended: Punctuation of numbered and bulleted lists.

Add also a comma after "firstly", "secondly", "thirdly", etc. to introduce a series of items.

Why do I need to learn Spanish? Firstly, it's the world's second most spoken language. Secondly, the demand for bilingual employees in the US has doubled for high-skilled workers. Thirdly, learning a new language will help keep you mentally sharp.

Do not add commas, however, when using these words as adjectives or nouns.

Emma's first choice was visiting Thailand. Her second choice was Vietnam and Laos.

I met the killer before the second and third murders.

Recommended: Commas with "Next"

2. When Not to Use a Comma After 'First'

The word "first" can be:

• an adverb (e.g., "He arrived first.")
• an adjective (e.g., "I sat in the first row of seats.")
• a noun (e.g., "I like the first.")

We do not typically add a comma after single-word adverbs of time, such as "first".

First I need to go to the grocery store.

We can use a sentence introduced by "then" after the "first" sentence. A comma after "then" in this situation is unnecessary.

First we dined at a Mexican restaurant. Then we went to the movies.

Avoid the comma when using "first" as an adjective.

Olivia was first in the rock-paper-scissors competition.

Alice was my first girlfriend.

When using it as a noun, we do not usually need a comma before or after "first".

I like the first better than the second.

Similarly, you should not use a comma when words such as "first", "second", etc. are the subject of your sentence.

The first is my favorite flavor.