...will be a secret no longer after this posting, but--c'est la vie--some things are too good to keep to one's self.
If you are anything like me, your mistakes are invisible when you are looking at your computer screen. Words left out, --ing words when they aren't required (which should be most of the time--an argument for another day) and even that all-important rhythm can be easily overlooked. This is because we read the words in our mind, not on the screen, and in our mind they are perfect. Ego is our greatest asset and enemy.
Get an e-reader and transfer your book to it. For some reason, seeing your words in a different format will make your errors stand out like a black fly on a wedding cake.
And now the great secret...
As you read, make notes in an mp3 player or some recording device. Only later, at your 'puter, do you make the corrections as you listen to your own sweet voice in your head on headphones.
I make notes like this:
"Small change. This is when Sha and Dee are first below the palace. When Sha asks where the passage of the Eye is looking at goes, Dee says, "I don't know." Instead, let's have Dee say she's explored the hall to the twisting steps down, but no further. This will make the reader curious what's down there. Find this by Sha asking "What's down there?"
Important to make some note of where you saw the correction, that you can easily find with a search.
Carrying an MP3 recorder has the additional advantage of allowing you a quick note when an idea pops in your head.
The only drawback to this system is you become dependent on it. Should you forget your MP3 recorder, you will feel like Darth Vader just cut off your hand.
