What to do indeed! Some writers like to sprinkle commas around like confetti while others will be very miserly in their use. Add to this a departure of comma style in America to Australia and Britain. It looks like such a tiny little tadpole but commas do love to roam and drastically alter the meanings of sentences and dialogue.
Take this quote borrowed from the good Bible and filtered through my unreliable memory. “I promise you today you will be with me in paradise.” I purposely left out any commas, now see what happens when I insert a comma. “I promise you today, you will be with me in paradise.” Or “I promise you, today you will be with me in paradise.”
In the first instance, I inserted the comma after the word ‘today’, which means that the speaker (Jesus) is making a promise today that the other person (one of the criminals on a cross beside him) will go to heaven at some unknown time. By inserting the comma before ‘today’ however, Jesus is making a promise that the criminal will join him on that day in heaven.
The comma is meant to create a brief pause in a sentence or dialogue. It can also be used to separate items in a list, such as: I saw monkeys, tigers, giraffes, lizards, snakes, dingoes, kangaroos and parrots at the zoo. Note that the second last item does not carry a comma before the ‘and’.
There are so many uses for commas that I could devote several blog posts to its use and abuse. And probably will. A common abuse of the comma is to use it to join what should be separate sentences, especially when the writer goes on a new tangent that makes the insertion of the comma a stalling point for any reader.
Commas are used after dialogue, again to produce a pause and a break before the attribution (the he/she said). Here is where American English can differ. In Australian style, the comma is placed directly after the last word of dialogue, and before the closing quotes. “I’m off to the circus,” he said. But in-sentence quotes take the comma after the closing quotes. The boy told his sister “I’m off to the circus”, as he headed for the front door.
It is often a matter of personal preference for the writer as to whether to place commas before and after names, for example, in a sentence. The sawmill boss, Gus Jones, was a tough man. Or The sawmill boss Gus Jones was a tough man. Either way, the the meaning is clear. However, once a writer adopts a style in regard to this, he or she should be consistent.