In my spare (Spare???) time, I like to draw. Portraits mostly. Sometimes wildlife too. I learned somewhere that after I think I'm done with a piece, I need to turn it 180 degrees and finish it upside-down.
What this does is fool your brain into re-looking at what you've drawn as the series of pencil lines it is, rather than a representation of something which your brain will "fix" into the intended image. The brain is an amazing thing. It will "fix" a thing, or fill in the blanks, without conscious effort so that you see what is meant to be, rather than what is. That's why a lot of us writers miss misspelled words without spellcheck. It's also why we have such a hard time editing our own work. Because we know what's meant to be there.
In the course of my work, I have found that it's much easier to critique others than to edit my own material. When you write a story, you're too close to see its flaws. Regaining objectivity is an important step in editing your own work. Sometimes you need to toss that manuscript in a drawer for a month. Sometimes you need to hand it over to your critique partners and let them have at it. Sometimes you just need to forget you're the one who wrote it.
Whatever method you use, if you do it right that "switch" goes back off in your brain and the work becomes what it is: a series of words on your computer screen or paper. And if you play it right, you pay attention to how the words flow. You notice how this work will affect your audience, and not what the words mean to you. And then you can edit with objectivity, sacrificing words or whole chapters for pacing if it's needed, or adding words to deepen or strengthen the story. Tough stuff. Never let it be said that writers aren't a brave lot.
I just wish I could turn a whole story 180 degrees and edit it upside-down.