One of the most common errors I see in manuscripts is comma splicing (also called run-on sentences)—a grammatical no-no. Comma splicing is the use of a comma to join two independent, complete sentences that can stand on their own. (I wrote a sentence, I used a comma splice, it became a run-on sentence.)

Here’s an example of a run-on sentence, along with four ways to fix it:

Joann bought a one-way ticket to San Diego, she vowed to leave her crazy family far behind.

First, you could break it up into two sentences:

Joann bought a one-way ticket to San Diego. She vowed to leave her crazy family far behind.

Or use a semicolon:

Joann bought a one-way ticket to San Diego; she vowed to leave her crazy family far behind.

Or use a coordinating conjunction:

Joann bought a one-way ticket to San Diego, and she vowed to leave her crazy family far behind.

Or use a subordinate clause (rendering the second complete sentence as an incomplete sentence or clause):

Joann bought a one-way ticket to San Diego, vowing to leave her crazy family far behind.

Remember, a comma just isn’t tough enough to take on two full, complete sentences. You’ll need the power of more industrial-strength punctuation if you want to avoid run-on sentences.