At the risk of sounding like Waldorf and Statler, there is something that makes me want to make snarky comments from my balcony: people who think that they just need to have their friend, significant other, dog, or stuffed bear edit their writing. Would you let your friends cut your hair? Sure, they could do it, but you would end up looking like Keri Russell in the second season of Felicity. So let me demonstrate this using the Good Idea/Bad Idea (a la The Animaniacs) method in reverse.
You give your book to your friend, Jessie. She looks over your novel. This could go down a few ways:
1) Jessie tears it apart. She tells you that she wants to punch your protagonist in the face. You have a huge fight, and it destroys your friendship. If you are lucky, you might have a tearful reunion on some daytime program (but one where they don't give away cars).
2) Jessie says she loves it and maybe fixes a few typos. This may help your ego, but it does not help your book.
3) She never reads it or only part of it. This is the worst scenario. You cannot help but wonder if your story is unreadable.
You hire an editor (like myself, ahem ahem). This is how it will play out.
1) You send your novel to your editor. You can relax knowing it is in good hands. You go on various adventures like looking at the otters at the zoo or watching a Gilmore Girls marathon (everyone is team Jess, right?).
2) Your editor returns your manuscript to you. Not only does she notice things like typos, but she points out plot holes, two-dimensional characters, and clunky dialogue. She not only finds these things, but she gives you recommendations on how to fix them.
3) You make the appropriate revisions while listening to the playlist your editor sent you. You return the manuscript to her. You also decide that "Shut Up and Dance" is the catchiest song ever.
4) She edits your writing again while you finish Gilmore Girls. You decide to make a campaign to make that reunion movie finally a reality.
5) She returns the edited manuscript to you (she has fixed the grammatical errors and typos for you). She discusses the lines that are unclear, and you fix them over Skype. You are done!
6) You celebrate! Your editor sends you a celebratory gift, and you dance to Beyonce together on Skype.
The best part: you avoid crying on daytime television!
Want to act on your good idea? You can work with me here. Let's get your writing looking like Keri Russell in Felicity in Season 4.