Comma Confusion

Chloe with the letter CMy agenda tells me it’s Tips Tuesday, which means I’ll share a writing tip.  And since today is the letter C, I’m going to talk about commas.  Don’t worry, I’m not going to stir up a heated debate about the Oxford comma (for the record, I’m pro Oxford comma, and they will have to pry it out of my cold, dead, typing fingers).  My comma tip concerns commas and conjunctions.

When critiquing, one of the most common issues I notice is the misuse of the comma before a conjunction.  In many sentences, the comma is needed, but it seems to have gone on vacation.  In other sentences, the comma is not needed, yet it insists on sticking its nose where it’s not wanted.  So how do we remember whether to use a comma in front of a conjunction or not?

When I consulted my friend Google, he gave me tons of links with rules mentioning independent clauses, dependent clauses, compound components, coordinating conjunctions – the types of boring phrases that made me tune out during elementary school grammar lessons.  If you want more technical explanations, you can check out Grammar Girl or university resources.  But when I’m writing/editing, instead of thinking about the whys and wherefores, it boils down to one simple test – can the parts before and after the conjunction stand on their own as separate sentences?

For these types of sentences, I like to think of the comma as a faux period... the substitute period... a placeholder period as the sentence decides to progress some more without a full stop.  

So when I’m writing and come up with a sentence like -
The adorable dog ran outside and chased a squirrel up a tree.
- I have to decide whether there should be a comma before the ‘and’.  If I think about the potential comma as a period, then I can see it doesn’t make sense to add a comma – ‘chased a squirrel up a tree’ does not stand on its own as a complete sentence.  
Now if the sentence were instead - 
The adorable dog ran outside, and she chased a squirrel up a tree.
- then you do need the comma because it’s two complete thoughts.  If you were to read that comma as a period, then both sentences easily stand on their own.  
I hesitate to mention this because I don’t want to confuse the issue, but some experts state that from a stylistic standpoint you can omit the comma between two independent clauses if they are both short.  This is a judgment call, but make sure you understand the rule before you break it.  
In case you need a refresher, a conjunction is a connecting word, and you can use the mnemonic FANBOYS to remember them:
And remember, to decide whether you need a comma in front of one of these FANBOYS words or not, pretend like it would be a period if you put it there.  If both resulting sentences are complete sentences, then add the comma.  If they don’t make complete sentences, then skip the comma.
Does this help clear up potential comma confusion?  Do you have any comma tips? How Cute is Chloe with her letter C?