When you write, you know you're supposed to follow the rules of grammar. It's what makes writing good, right?
Few writers are going to put a paragraph like this in their books:
"John watched Mary walk away, crying as she went because she was so so sad because he hurt her when he killed her pet dog in a drive by banana crushing accident. When she reached the end of the drive-way, she turned around and shook her fist at him. I'll get you yet, you cold-hearted bastard son of an egg-sucking yarmulke, she cursed."
Horribly structured sentences, riddled with grammar and punctuation mistakes, not to mention just poorly written garbage.
When you write, you stick to the rules of grammar because they're what make your book readable. However, every writer wants their writing to be unique, so we're tempted to break out of the mold just a bit.
Some writers use fragments, others use long-winded paragraphs (here's looking at you Dave Barry), and still others structure their sentences in unique ways that are grammatically correct, but only barely.
There are some writers that can get away with it, and they do so VERY well. They break the grammar rules, but they do so with such aplomb that we hardly notice it. We're so caught up in their stories and their characters that the flouting of the rules goes by unnoticed.
And then there are the newbie writers like you and me who try to sneak these things into our books, and we fall on our faces. Our writing skills just aren't where they should be to break the rules just yet, so we end up making our books weaker and less enjoyable as a result.
For your own sake, at least for now, stick with the rules of grammar and good creative writing. Until you can find your own way to break those rules the RIGHT way, follow them closely. Sure, bend them a bit, but make sure that your writing is grammatically correct and readable.
Helpful hint: Use THIS TOOL to see how readable your writing is.
Just to make things interesting, here's the topic of next week's Writing Mistakes post: Following the Rules Too Closely.