Five Steps For Editing a Manuscript:
1. Spell and Grammar Check: I do this as a quick check, and I don't believe everything Microsoft says about grammar. There's a lot the word processor doesn't understand. However, it's a good start.
2. Use the Find function for spotting passive voice and other common problems I have. If you use the Find function for words like is, was, were, very, etc., you will discover the passive-voice sentences. I also use it for other common problems I have--words I tend to overuse; names I may have misspelled (I find the misspellings, or use the Replace to change them all.)
3. Print and read it. I always catch more stuff when it's on paper than when I have it on the computer.
4. Read it out loud. This lets me check for flow of narrative and hard to follow sentences. Also, by reading it to my kids, they will tell me what works and what doesn't.
5. Read it backward, one sentence at a time. By isolating each sentence from the narrative, I can better analyze it.
Usually after that, I will give it a final read, beginning to end, on the computer.