Aaron Sorkin is a god when it comes to dialog. Seriously.
For those unfamiliar with the name, Sorkin is the writer and creator of such delights as "The West Wing," "Sports Night," "Studio 64," "The American President," and "A Few Good Men." Watch any of these, and you'll hear the style of his writing and how he puts words together so they hit the ear just right.
What does this have to do with writing, you ask? Everything.
One of the things agents say they look for in a query (and a book) is the author's voice. Developing your voice goes hand in hand with how you put words together and how they sound when you're done. Watch enough Sorkin, listen to enough of his characters talk, and you'll be able to peg his work when you hear it. That's voice. (Joss Wheadon is also extremely good at this)
As West Wing character Sam Seaborn would say, it's the cadence. Sentences have rhythm and the words you choose affect that rhythm. That's why leaving in an adverb might be better for the sentence than taking it out, or using an "he said as..." tag works better than just showing the action. The flow of the words matter more than the grammar of them.
Grab a few of your favorite books off the shelf. Go ahead, I'll wait.
Back? Okies, now, randomly pick a page, and read a few paragraphs out loud. Listen to the words, the structure, the rhythm of the sentences. Now look at your own work, and do the same thing. What does your voice sound like? Do you hear a rhythm that is uniquely yours, or does it sound general or -- eek -- even bland?
If you like what you hear, celebrate, because you have that all important voice. If you don't like it, then think about what you can do to develop your voice. Look at your word choices and see if you're letting the technical aspects of writing get in the way of the cadence, the rhythm, and the sound. "Perfect" writing can sound flat, while an odd combination of words can evoke emotions.
A story is so much more than just listing things that happen. This is why a lot of description can feel list-like -- it is a list of things. Study your sentences to see if they all have the same rhythm and length. Read them out loud (the best way to hear it). Do they all have the same structure? For example...
"She's not here," Bob said, crossing his arms. "I haven't seen her since we encountered those six zombies in Tulsa." He stared at the man holding the gun."Did you look for her at the factory?" The man was an idiot.Hear that flatness? The clunky way the sentences flow (or don't flow) together? Details are stuck in there more for the reader's benefit than like real people speaking. Kinda boring right? Now try the same details, but vary the length and structure, and toss in some of your POV's personality.
"She's not here." Bob crossed his arms and stared at the jerk holding the gun. Idiot. "Haven't seen her since we gave the slip to a sick-pack of walking dead over in Tulsa. Did you try there?"Better right? That's what voice and rhythm can do for you. Like music, it pulls you through the story and makes you hum along.
There are only so many stories in the world, but how you choose to tell that story is what makes you stand out. Don't just focus on what your words say -- listen to how they sound as well.
Do you read your work out loud? Do you edit (or write) for rhythm? How often do you notice the rhythm of another writer's work? Does it stand out?