"Use Commas after Conjunctive Adverbs and Transitional Phrases at the Beginnings of Sentences" was written by Joseph Moxley, University of South Florida
Although our modern style calls for using as few commas as possible, you should generally place a comma after conjunctive adverbs and transitional words because they modify the entire sentence:
- Nevertheless, we must push forward with our plans.
- In other words, you're fired. Hey, I'm just kidding.
Because commas cause readers to pause in their reading, you want to use them sparingly. Although logic would suggest that it makes sense to follow coordinating conjunctions with commas, convention does not call for this usage unless the conjunction is followed by an introductory phrase. Thus, it would he inappropriate to write:
- Yet, I think we should go ahead as planned.
When a short phrase follows the conjunction at the beginning of the sentence, however, it is appropriate--although not absolutely necessary--to place a comma after the conjunction:
- Yet, as I mentioned yesterday, I think we should go ahead as planned.