When editing, there becomes a point where you sometimes cannot tell if you are making something better or worse. That is when you need a second opinion. One way to do this is to put the writing away for twenty-fours or more before taking another peek. When you uncover your work again, you will be coming at it with a different perspective and attitude. The work will have cooled off and your subconscious will have had a chance to chew on it for a while.
Another way to see your work fresh may be to read it out loud. When you do this you use more than your eyes to do the reading. Reading out loud involves your mouth and your ears as well. As you go along your ears are more likely to find extra, repeated or missing words. They can also detect the difference between barley and barely. Because these are all examples of properly spelled words, you cannot count on auto correct for these. This sets up another filter for catching mistakes.
I was sure this was a very good story although I would not know truly how good until I read it over the next day.
At the point where you can no longer stand to read it over one more time, it is helpful to look for a friend willing to read over your work. Find someone who will be honest with you but not brutal. We may feel like we want the bald, naked truth, but the real truth is writing needs to be built up not torn down. You are asking for help not a wreaking ball. Writers should be constructive in their criticism with each other. Even if the work needs to be completely rewritten from the second reader’s point of view, there is an appropriate and helpful way of communicating that.
A writer should also be judicial with comments from others. You do not have to blindly accept advice. One way to decide whether a suggested change is helpful is to save your work under a new name using the “save as” function. Then make the changes in this second document instead of the original. Read both versions and see which one works better for your piece.
However you edit, remember to keep doing it. Editing is the heavy lifting of the writing process. Some authors send their work through a hundred revisions. That may be an extreme, but it certainly can’t hurt the quality of the work as long at the writer is coming at it with a fresh eyes.