In this article we'll focus on the use of commas after introductory words or phrases. There are a few rules, mostly to indicate a natural pause in the sentence and to avoid sentence confusion. In many cases it is the writer's choice. Here are a few guidelines to follow.
DO use a comma:
After introductory exclamatories and after expressions of affirmation or negation.
Well, it's about time. Oh, you shouldn't have! Yes, I'd love to.
After an introductory clause.
As I told you, the principal won't be back until Monday.
After an introductory prepositional phrase of more than four words.
After driving for more than eight fun-filled hours, we finally arrived at the motel.
After an introductory verbal phrase, appositive phrase, or absolute phrase.
Having formed an instant bond, the boy and the puppy quickly became inseparable.
In order to give a good estimate, the plumber spent over an hour investigating the leaky pipes.
A lawyer from Texas, John Stetson is an expert in copyright law.
After introductory transitional words.
However, I never said I would actually attend the party.
Of course, I wasn't actually invited…
Do not confuse a gerund with an introductory phrase.
Watering the lawn is a good way to attract birds.
To tackle the subject without any research would be foolish.
NOTE:As with many elements of creative writing, comma usage generates much debate. Many experts recommend separating all introductory elements with a comma. It makes for a natural break or pause, and it contributes to better comprehension. Others argue that if the sentence is clear without the comma, and the introductory element is short, the comma is unnecessary; ultimately, it comes down to personal preference and what works best for the reader.