When you've addressed all the big issues in your manuscript, given it to still another batch of advance readers to confirm that your plot and characters are working, then it's time to pull out the microscope and examine it up close.
First step: Print out the manuscript. While some final polishing can be done on-screen, reading and editing directly in the electronic file, there's no substitute for the perspective that printed pages gives you. Somehow, errors that slip past on the computer screen seem to pop off the printed page.
Expect to go through your manuscript at least three times to get the job done.
“What's nice about writing is that nothing's set in stone till it's finished. It's only then that you hang yourself out to dry.” — Evan Hunter (Ed McBain)
Strong Starts and Finishes
First impressions and final impressions are what readers notice most. So lavish some special editing attention on all these starts and finishes in your manuscript:
Make the first line, the first paragraph, and first scene as strong as you can make them.
Introduce each setting vividly.
Make each main character's first appearance memorable, establishing that character's physical presence with a few telling details as well as the character's voice.
Pay special attention to the first and last paragraphs of each scene.
Make the last page, the last paragraph, and the last line as strong as it can be; leave the reader with something to think about.
Tighten Each Scene
Read each scene through and assess whether it delivers everything that a scene should. A flabby beginning should be tightened. If it starts too early, cut to where things get interesting. Floating characters need to be anchored in time and place. An ending that dribbles off should be trimmed. If there's no conflict in the scene, look for opportunities to insert some.
And most of all, make sure that your novel needs every single scene that's in it. If you can cut a scene and the story won't suffer, cut it!
Here is a checklist of things to look for in each scene:
Strong start: Does it engage the reader right away; are you starting it as late as possible?
Clear orientation: Is it clear to the reader, within a paragraph or two, where and when the scene takes place and who is there?
Conflict: Every scene should have some tension or conflict; at least one character should feel off balance.
Arc: From beginning to end, something should change in the course of each scene, even if it's nothing more than a character's emotional state.
Strong finish: Does it end strong and as early as possible, or does it just dribble off?
Tweak the Chapter Breaks
When your scenes are as tight and compelling as you can make them, then examine how you've grouped them into chapters. Chapters can be long or short. Use the placement of chapter breaks to add to the momentum you are trying to create in the story.
Be aware that many readers like their fiction served in twenty-minute chunks. So consider breaking up a chapter that goes on longer than that.
Where you want momentum to build and the reader to keep turning pages, break a chapter in the middle of scenes at a cliffhanger moment. Where your storytelling is more leisurely, then break the chapter at natural scene breaks.