How do you know when you're finished revising your manuscript?
After the second or third pass, it's easy to believe that you're done.
You've revised verb tenses and word choices. You've caught typos. You've polished each sentence until it shines like polished silver.
But are you really done?
If you're working with an editor who you can trust, you can share the manuscript and listen to feedback.
It's the same with a writing group. If you trust the other writers in the group--and why would you be in a writing group you don't trust?--you listen to their feedback.
If you prefer to work on your own, though, you have a slightly different challenge, which is, ultimately, the same challenge that every writer must face.
You need to listen to your inner voice, which can be deceptive at times.
You need to keep digging, keep asking yourself what's missing.
What am I forgetting? What does the reader need in this moment? What does my character want, and what's keeping him or her from getting it? And what does he or she do to reach his or her goal?
To answer these questions, you may have to put your manuscript in a drawer for a while.
A day, a week, or more.
That's how you can gain distance and change your perspective.
That's how you can return to it with a clearer eye and see gaps or missing pieces that you couldn't have seen when you were so close to it, working on it from the inside, so to speak.
Each time you revise your manuscript, you need to see it the way a reader will see it.
How might your words strike a reader? What images and scenes will make the greatest impact? Why does the plot unfold the way it does?
Working on revisions in this way becomes a process of listening more carefully and looking more closely so that you (and ultimately your reader) are able to slip inside your characters and can feel what they're feeling.
As you keep reviewing the manuscript, you're listening for inconsistencies, for the gaps that you couldn't see on the previous pass, for the issues that you can expand or delete.
The secret is patience.
Give yourself time.
As many writers have discovered: "Time is the best editor."