I'm also helping a few others with their own work. And a few years ago, I taught creative writing to eager and enthusiastic young writers. When reflecting on some of the things I've come across while wearing my editor's hat, I came up with just a short list of common mistakes writers make when creating dialog. Dialog to me is key to a good book, and even the most season writers make the following mistakes:
Long Winded. Are you a people watcher? I am. I'm also an eavesdropper. I love listening to people talk. Have you noticed that 99% of the time, people speak in three-four sentence blocks per turn? I've come across rough drafts where characters will go on and on. And it's easy for a writer to do. Unless your character is giving a speech or something, stick to shorter blocks of dialog.
And if you find yourself making your characters speak in Emancipation Proclamation type of dialog blocks, you're probably doing the next big dialog no-no...
P.S. Don't write dialog that imitates EXACTLY how people talk. Fill your dialog with short hand slang and um and uh all over the place, your reader will stumble. Keep the more natural "filler" humans use down to a minimum.
Information Overload. Dialog is supposed to have purpose. Move the story. Propel it. And that's why it's easy to put too much information in your dialog. Readers are smart. No need to spell everything out. No spoon feeding. It's condescending to your reader and a HUGE turn off. Let dialog build suspense, reveal motives, and show conflict.
If you're going to use dialog to introduce major elements or describe a missing scene, please make sure it's natural and flows. Don't pull a Shakespearean aside and have a character spell stuff out to the reader (a la Ferris Bueller). Not only does it show laziness, but it also looks very amateurish. Make your book an information dump-free zone.
Name Calling. I see this a lot in beginning writers' work. When you watch TV or movies, you'll notice characters are constantly calling each other by name when they speak. This makes sense, as it helps the viewer figure out who is who. But we don't do that in real life. Could you imagine:
"Hey John, what are you doing?"
"None of your business, Jim."
"You shouldn't be doing that, John. It's dangerous."
"Jim, keep your mouth shut."
Not only does this dialog sound really stupid, it's the mark of an amateur. I would say you should have no more than a handful of instances where characters call each other by name when they speak. Writers use tags to help readers figure out who's speaking. Speaking of tags...
Stupid Tags. Tags help - but don't try too get to fancy with your tags. From the reader's perspective, the word said is nearly invisible. It flows. It works. Don't crack open that thesaurus to find new tags unless it's incredibly important and necessary. Other good tags are: replied, asked, questioned, answered.
Bad tags: cajoled, seethed, ejaculated, hissed, sneered, snort, gasp, and moan. There's more, but I just drew a blank. But you get the picture. Example: it is physically impossible to hiss, gasp, or snort actual words. Ask any speech therapist. And yes, I did read one manuscript from a college student that used ejaculated as a dialog tag.
Go do a SEARCH for the word hiss in your current WIP. Unless you're writing about a snake, chances are you need to get rid of it. And if it's being used in dialog tag, most certainly it must be EXTERMINATED (in my best Dalek voice).
Use alternative tags sparingly! But get rid of dialog tags that are either lazy and/or redundant. Examples: admitted, confessed, taunted, noted, examined, concluded...There are so many! These tags can be sprinkled here and there - but many writers use these when they're just being plain lazy asses. If the reader can't figure out that a character is taunting without the use of that tag, then you're not doing your job as a writer.
Adverbial Tags. While we're on the subject of dialog tags, get rid of adverbs. No seriously (ha). Get RID OF 95% OF YOUR DAMN ADVERBS. The suck. They show laziness. And putting them in your dialog tags sucks atomic donkey balls.
"You need to stop doing that," Jim hissed accusingly.
Okay, get rid of hissed, because it is physically impossible to hiss those words. And get rid of accusingly. If you need that to explain to the reader what's happening, you're assuming your reader is a moron. Lose all adverbs. Zap them, kill them. Hang 'em up, and then burn them. You want be be descriptive? Add a little action.
"You need to stop doing that," Jim said as he snatched the remote control from John's grasp.
*Caveat: There are a few instances where you might need an adverb, but any adverb should still be a red flag.
"Thanks a lot," she said bitterly.
Okay, bitterly is fine there. Because from her spoken words, you can't tell that she's bitter. But like I said, keep adverbs to an absolute minimum. Don't be lazy. Do a SEARCH for ly in your word processing document and kill those unnecessary adverbs (A.K.A. vermin).
Movie Scripts. One of the worst things a writer can do is create dialog as if it's a transcription of a conversation. In addition to tags, add a little bit of action - give the reader a clear idea of not just what is being said, but what is happening. You can also use a little bit of action instead of a tag:
Jim ripped the remote control from John's grasp. "You need to stop doing that."
If you have one line of pure dialog after another, unless it's a very quick exchange, readers get bored. Break up dialog with tags AND action. You're not writing a movie script.
Local Color. Okay, this one is very tough. And even NY Times Bestsellers have to work hard on this. If you have a character that speaks with a foreign accent or some type of dialect (regional or otherwise), you need to still convey that, yet not have it be such an obstacle that the reader needs a Little Orphan Annie Decoder Ring to figure out just what the hell is being said.
"Wen back in de day, dey said dere wasn't no way de kin 'kep 'em comin'," said Wilbur.
I get it. The old man is from the South. But this is such a jumbled mess. Try this instead:
"When back in the day, they said there wasn't no way they could keep 'em coming," said Wilbur.
Again, less is more. In my current WIP, my main character speaks without using contractions. There are some cool things you can do to make dialog a great part of characterization. And infusing local color is one way. Just don't abuse it, okay? This ain't no Hooked on Phonics!
* * * *
* I hope I could be of some help. I know I have to keep this stuff in mind with my own work, as I'm just as guilty of these transgressions as anyone else. But like everything in life, there are always exceptions to the rule. If you have a character that speaks only in adverbs, if your character is verbose and won't shut up, or if you have a pair of characters that call each other by name when they argue - all of these cases call for the dialog rules to be broken (or bent).
But I still think if you really look hard at your manuscript and those alarms go off in your head, hopefully you're just one step away from creating a better product.