I'm writing this in the middle of National Novel Writing Month, as part of my attempt to procrastinate from that thing I'm supposed to be working on (it's not exactly a novel, but never mind that), while still producing some form of written manuscript. It happens. Actually, National Novel Editing Month isn't until March, but I don't want to wait until then to write the essay on editing which I'd rather write right now.
Instead, I'll probably wait until March to write the novel I'm supposed to write right now.
Speaking of waiting, though, there is a reason there's a four-month gap between the time you're supposed to write your novel and the time when you edit it. Letting the manuscript sit in a drawer for twelve weeks gives you fresh eyes, and perhaps more importantly, it lessens your emotional attachment to the words, some of which you will inevitably need to revise or cut. When it comes to letting a story sit, it's a fine balancing act: you need to get some distance, but you also need to maintain enough interest in the story that you'll be motivated to return to it. It's all right, indeed even desirable, to remain fond of your work. But that fondness should be less the kind that makes you want to run out and buy a My-Novel-Is-The-Nobel-Prize-In-Literature-Winner-Your-Honors-Student-Writes-Book-Reports-On bumper sticker and more the sort that inspires you to make it the best it can be, rather like a parent raising an honors student (feel free to disagree with this metaphorical flourish; I've met enough honors students that I couldn't blame you).
If you're like me, you're lucky and after leaving your story to gather dust in a computer file for a few months, you'll suddenly develop a nagging curiosity about what you've really written. As you take a look, you'll either be pleasantly surprised and consumed by the desire to get this piece out there into the world, or you'll be horrified and driven by a penitential desire to make things right. Either way, you're ready to edit.
Editing is a matter of taking words that do not do things and turning them into words that do. A story is made up of words that do things—that explain or illustrate setting, character, or situation, that move the plot forward, that are vivid and interesting. Words that do not do things aren't actually part of your story. They're vague, redundant, or extraneous. They don't give the reader a clear idea of what's going on, or they repeat what the reader already knows, or they're just written throat-clearing. Words that don't do things waste the reader's time.
(This doesn't mean they wasted yours to write in the first place—for one thing, sometimes throats need to be cleared. Sometimes words that don't do anything had done something originally, but the story evolved past needing them. Or the story may evolve as you revise it, to the point that some of the words which did nothing suddenly do something. Making this change is one of the primary goals of revisions.)
Sometimes an entire scene may be made of words that do nothing. Make the words do something or cut the scene. Make every character do something, preferably something no other character can do, or fire them. If you feel really bad about it, you can write about the character in another story someday.
Another division I find helpful is that between 'loose' and 'tight' paragraphs. In a tight paragraph, each sentence locks into the next. Every line is focused, on-topic. Every sentence is needed. And the links between them are clear, so the reader isn't left confused as to how they wound up where they are.
However, first drafts are usually full of looser paragraphs, where ideas are thrown onto the page as they occur to the writer (and some ideas which are needed don't quite make their way into the story). The writing is confused and unclear. It can be vague or repetitious, and often jumps around—because words that do nothing don't illuminate or illustrate or lead logically to the next words and sentences. They're just there. Hanging loose.
The loose and tight division scales down to each individual sentence (or even each phrase or clause of a sentence) and up to loose and tight chapters, plot arcs, and even characters. Minor characters should be tighter, as should subplots. Beginning chapters should be very tight (you have a lot of background to give the reader and not a lot of space to do it in before you're boring them), while they're usually the loosest in a first draft because the writer is still struggling to find their footing.
As you revise, your loose paragraphs will tighten. You'll find the concepts and descriptions you're missing and add them. You'll add connections between unconnected ideas. You'll delete words and sentences and chapters that don't accomplish things. In their place, you'll put rich descriptions, vivid action, and fascinating ideas. The resulting story will be sleeker and more vigorous, and hopefully of more interest to the reader.
This Process In Action
The first thing I do is reread the chapter, scene, or paragraph I'm about to revise. Are the words I'm using accurate, clear, and vivid? Do they actually describe what happened in the story (as I remember it, months after writing it—and if my memory fails, can I reconstruct it from my words?). Are there things I forgot to add—explanations and background, and illustrative example or metaphor, or even a segment of plot arc? Add these bits into the loose paragraphs and tighten them up. Be sure, of course, that the explanation is actually needed and not repetitious.
Make sure your plot arcs are complete and logical and well-grounded—revision is a great time to add foreshadowing or echoing, once you know what's going to happen. What about characters—are they behaving, well, in-character? Is their dialogue engaging, and does it further the plot and illuminate their personalities and relationships? Does their vocabulary makes sense given their background and situation (street urchins do not say 'indubitably,' and princesses rarely say 'f**k that s**t')?
Once I'm sure everything makes sense and the writing is fairly 'tight,' I do a final check for repetition of words and any of my personal clichés. For example, when my characters pass out 'darkness' tends to 'fall down' upon them, and if my characters are kissing and dialogue occurs the odds are better than even that they'll 'whisper the words against their lover's lips'. I think that was breathtakingly romantic the first time around, but nobody was impressed by the third occurrence.
Those are my bugbears; you, being a special and talented and unique individual, will have your own. Watch for them. Eventually you'll come to hate them so much you'll never write them again, and move on to new clichés. The painful part of fixing echoes and redundancies is that sometimes the word you've repeated really was the best word for both situations, the most accurate, clear, and vivid. This is when it helps to have a wide vocabulary—you'll be able to at least find a second-best word, and sometimes everything works out wonderfully and you discover there's an even better option once you start searching.
So much for wrapping things up; where does one start to revise an entire story? First, be sure you have reread it from the beginning through to the end, so that you now have a sense of how the plot unfolds and the pacing works (or doesn't work). After that, you can begin with whichever parts you're most confident about. Polishing a section that is already pretty tight, clear, and strongly written will encourage you as you move on to areas that need more work. However, and perhaps paradoxically, I also make more progress when I start on a section I'm most confident is not strongly written. Fixing obvious mistakes and catching those plot holes which have you sitting bolt upright in the dark of night shouting "No! Surely I didn't write something so stupid!" will at least give you a less painful draft to continue your revisions on. If it's any comfort, it's still a sign of your growth as a writer to recognize those 'obvious' mistakes, even if you couldn't avoid making them in the first place. And now you know to watch out for them in the future. Most of the improvement I've made from first draft to first draft comes from dreading the repetition of mistakes I discovered during a grueling revision process. And I improve even harder and faster when the mistakes are discovered by someone else. I owe much to a particularly cruel beta reader.
But it's perfectly possible to create a polished second draft without the influence of a literary sadist. On its most basic level, revision is no more difficult than writing the first draft, putting words down one after the other on a blindingly blank page. At least with revision you are working with a positive, a collection of words in semi-coherent order, rather than pure nothingness from which you must create. Not that there isn't creation in the editing process! Once you clear out all those empty words that don't do anything, you have room to create more sentences, sentences full of words that do accomplish things—that tell your story.
Update 3/2014: A lot of the information from this chapter-plus a whole lot more-has now been published in my book, The Starter Guide for Professional Writers. I'll keep my plug short, but if you want to find out more about the book, which is jam-packed with information to help new writers with improving and publishing their work, please do check out my profile!