It's a word commonly tossed around between writers, editors, etc ... and we all nod like sages and say "Ah, yesssss. Flow."
What is flow? If you dissect "flow", what will you see?
Flow is exactly what it says it is. When you think of "flow", you think of water. And water runs smoothly, without interruption (unless, of course, there's a dam, and we're going to ignore that part for the sake of the metaphor).
How do you know if your writing flows?
First of all, follow the #1 Rule: READ YOUR WORK OUT LOUD.
Seriously. And I don't mean mutter it out loud. Read it like you mean it. And if you're reading along, thinking how beautiful the story is, what a great writer you are, how the world is going to love this ... then all of sudden a word sticks in your mouth, well, that is what I call (in the very technical Genevieve dictionary) non-flow. STOP. Now, what made you stop (aside from my commanding voice)? Was it a specific word? Was it the way the sentence was formed? Maybe switching a verb will help. Maybe moving the subject and object around will ease the roadblock. Maybe trashing the entire sentence will clear it up. It may seem rough, but really, do you need that sentence? Or is it just there to contribute to word count? Is it a need or a want?
Okay. You finished fixing that. Take a deep breath and read on. No cheating. READ IT OUT LOUD. This time you don't exactly trip on a word, but you kind of skip over something that makes you uncomfortable, or that you don't think matters. Well, it does matter. It matters that you get rid of it. Analyze that sentence and either remedy the situation or cut the whole thing.
The thing is, in writing, every sentence, every word counts. You can't write the most brilliant opening sentence ever written, then follow it with a dud. Take it seriously. Take the time to examine everything.
Does it make sense?
He closed the window and exhaled, watching the silver coils of his cigarette smoke drift into the trees.
Hands up everyone who sees the problem with that one. Fix.
Does it matter?
It was raining so hard she thought they might all wash away. It made her think of laundry. Crows struggled through the wind ...
Okay. So that's a lame example, but it's hard to come up with these. Anyway ... Laundry? Pretty sure that's unimportant. Delete.
Does one paragraph resemble another?
By this I mean ... let's say the opening paragraph is beautiful, brilliantly poetic, intelligent, soul searching stuff ... and the second is a clean description of a door. Make the door poetic, or make the other stuff cleaner. One or the other. Not both. Fix.
Does the destination justify the journey?
This is tough because you don't want to get too nit-picky. Here are a couple of examples, both of them wrong:
1) He was sitting in the love seat when the doorbell rang. "Hello, George."
2) When he heard the doorbell, Frank leaned forward, tightened his thigh muscles and unfolded his kness, rising to his feet and placing one foot in front of the other ...
Does paragraph 2 follow paragraph 3 or is it too much of a leap?
You don't have to stay on one subject throughout every single paragraph, but make your bridges smooth. Don't go from talking about Cindy's mother to the faulty carburater in Fred's Honda, unless you bridge them somehow. Maybe she drives the car to the shop?
Go with the flow, grasshopper. Relax, breathe and READ OUT LOUD.