Q. Some editors at my office believe the word so should always have a comma after it when it begins a sentence. (“I am a clumsy person. So, I try not to wear white on days when I will drink coffee.”) I believe so should be treated like and or but; they think it should be treated like thus. Yet they don’t use the comma if the clause is in the second half of a sentence. Is the comma optional, never allowed, or allowed only in certain situations?

A. So that begins a sentence or clause does not take a comma unless a parenthetical phrase or clause follows, and even then it’s sometimes optional: So, in light of his threats, I had to hide the chocolate. Sometimes a writer hears a pause after so, and if a writer really wants us to pause, then it’s hard to deny him a comma. But if a pause is that important, perhaps an ellipsis or dash is called for.