Today's lesson:
The Most Common Punctuation Errors You Probably Didn’t Know You Were Making

Inattention to the adjectival phrase: An adverbial phrase’s location in a sentence will determine whether you should use a comma between it and the main clause. An adverbial phrase is any cluster of words that modifies the main clause. It can determine how, when, why, or where the main clause is being performed.
Example [phrases and clauses labeled in brackets]: If the adverbial phrase comes before the main clause [adverbial phrase], use a comma [main clause]. Don’t use a comma [main clause] if the adverbial phrase comes after the main clause [adjectival phrase].
Failure to use the Oxford comma when it really counts: There has been much debate recently on whether the Oxford comma should remain a grammatical rule. Many people have opted to drop it altogether; however, there are some instances in which it is absolutely necessary.
Example: “I’m going out later with my parents, Anna and Paul.” The readers don’t really know this, but my parents’ names are not Anna and Paul. I’m actually going out later with four people: my parents, Anna, and Paul.
Take note that there are rare instances in which using the Oxford comma can create ambiguity, and in those circumstances, it should be eliminated.
Example: “I’m going to a movie with my mother, Carol, and Jesse.” In this case, readers might mistake Carol for my mother, when she is one of two friends who will be joining my mother and me.
Using a comma to break up a list of two: This one should be a no-brainer, but I see it far too often. Even if the list is comprised of actions, never use commas unless that list contains three or more items.
Example: After we go to the store, we’ll organize the kitchen, and make dinner [wrong]. After we go to the store, we’ll organize the kitchen and make dinner [right].
Failing to use a comma when addressing someone: This is a problem I see often in dialog. Most of us have read the comical example, “Let’s eat Grandma!” Unfortunately, far too few people actually heed the rule. Unless you’re actually planning on eating Grandma, don’t forget the comma.
Using a semicolon before a participle phrase: Far too many people have no clue how to use semicolons, being under the impression that there are places in which they can be used interchangeably with commas. This is rarely true. Never use a semicolon unless you have a complete clause on both sides; those clauses should also have a strong enough relation to one another to merit a semicolon rather than a period. (See how that works?)
Example of improper semicolon use in a participle phrase: When they got to the beach, they made a sand castle; taking great care not to knock it over [wrong]. When they got to the beach, they made a sand castle, taking great care not to knock it over [right].
Using commas in a list in which semicolons are more appropriate: Going back to the necessity of using commas in a list of at least three items (the debate over the Oxford comma aside), there are a couple of instances in which commas need to be replaced with semicolons. The first instance is when listing items that, in themselves, have commas. The second is when listing phrases that come after a colon.
Examples: We got up early yesterday, having set the alarm for five; ate a quick breakfast of eggs, toast, and juice; and got to the conference by seven. The group made the following mistakes: heavy use of grammatical errors; using numerous run-on sentences; and failure to use spell-check.
While you might have readers who also do not know the rules, there is always a chance that editors, agents, or reviewers reading your work do. If you take the time to know and understand these rules, your writing will be sharper and you will be able to present it to the world with confidence and skill.
Until next time, my pretties! (Insert evil cackle.)