Editing is one of those things that you hear in the publishing world but when it comes to doing it, we drag our feet. It takes a lot of work and no matter how many times you read your story, there is always going to be a mistake. Not only that, but if you're like me, after I read my own story so many times, I have it memorized and therefore, will mentally read what's not there causing me to skip even more mistakes. It's a very frustrating process, but let me just say, it's an extremely important part. I found that when sending out your work, this is one of those things that publishers and literary agents look at when determinging if your story is fit for their company. In other words, don't skip on this part.
Editing your story is one way to go. As I mentioned above, you will have a tendency to skip over mistakes with the familiarity of your book. My recommendation would be to get someone to take a turn editing your story. You can have a friend who rocks at grammar do it for you or, pay an editing company to do this. There are several stand alone editing companies out there that will charge a flat fee to edit your story for you, one such being The Editing Hall. Not only will they check the grammar, but they will provide an honest opinion of what works in your writing and what makes no sense. It all makes sense to us when we write it because it's coming from our heads, but that may not always be the case for your readers. Getting an outsider's opinion is the best solution for this. That being said, another key componet to keep in mind during this part, is the editor is not out to hurt your feelings but make your story the best possible version of itself. When I had my first story edited, I cried because I thought the editor was taking personal stabs. She wasn't. She was just trying to make my story the best she could. You have to have thick skin for this part of the writing process.
In the editing world, there are two types of editing. Copy line editing and proofing. Copy line editing is what you do in the very beginning and takes the most work. This is where you not only check your story for grammar but also the flow and overall story. This is where you're going to see the most change to your baby. The second stage is the proofing. Generally someone who has not seen your story will take this level on because they are more likely to catch the smaller grammar mistakes that you and your copy line editor may have missed the first two rounds. This is where you'll see the least amount of changes. Now, your book should be ready to publish!
I hope this article has helped you out but keep in mind, this is overall just my experience and by no means the standard written in stone. Have fun writing!