There are a lot of ways to edit, but the three I like best require you to sit through your story with a different mindset each time: the Reader, the Writer, and the Character/s.
The Reader: Pretend you’re reading your story for the first time. What do you, as a reader, expect in a book? If that’s hard to think of, try reading a similar book with a similar plotline (if your story is a mystery, then read a mystery). Keep track of what you think of when you read that. Do you think that there’s not enough tension? Check your book for that. Do you think that the characters are too flat and general? Add a few quirks to yours. Etc, etc. Does the story completely twist and surprise you in a way you didn’t expect? If that’s a good thing in your story, then keep it; if it’s not, if it’s too out-of-the-blue — even though it seems a part of your story now because you’ve been working with it so long — cut it.
The Writer: The main question you want to ask yourself while reading through you story as the writer, is “What do I want my readers to know?” What is your theme? What do you want your readers to leave with when they close the book? Make sure every scene is poignant in the reader’s mind. Also, as the writer, think about the way you wrote the story. Are the words you used too big? Do you use one word over and over? Is your style too brief or too lengthy? Is your grammar correct? Be sure to remember what kind of book you’re wanting to present while going through the writer’s POV.
The Character: Lastly, picture yourself as your characters. Each one that’s in the scenes you’re viewing. Ask yourself, as your character, “Would I really do this?” A lot of the times, when I’m just writing and writing and writing, my characters seem to blend together and have little distinction. Give yours a personality and make sure their actions and words are consistent.
With these three different mindsets, I think you can get a some good editing done, editing that encompasses everything you need to.
~ J. Dominique