Yeah, I know I know, you sell it. Or publish it. Or so on.
But really, what do you do once you've written the final words and tagged on "THE END". Well, just because you wrote those final two words, it doesn't mean you are done. You have to go over it and over it and then over it one more time.
Once you've corrected every single little error you can find, then you give it to someone else to read to tell you whats wrong with it. And though family and friends are great at giving you positive feedback, or at least neutral feedback, you need someone who will tear it apart for you and tell you what is wrong. And not only what is wrong, but WHY it is wrong. Is there a problem with your plot? Is your character pretty boring, or irritating, or not likable enough to keep the reader engaged? Then you also hope this reader will tell you what is RIGHT about it. Every writer wants to hear praise, but it's the best when you can get praise for what you did well, along with suggestions on how to fix what is wrong with it.
My most recent manuscript was finished toward the end of July (just before my baby was born) I let it sit for about a month while I enjoyed my newborn. Then got back at it in September and worked on fixing what I could find wrong with it. I sent it out to about 5 readers who took the time to look through it and tell me what they liked and didn't like. Then I spent another month applying those edits. I sent it out again to 4 other readers and back to 1 of the first 5 to have another look. Now I'm in the process of fixing it again. And can I tell you this version will be so much better than the first one I had finished in July. Critique groups are so so so so so important.
Another thing to work on once you get the story written is to work on a query letter, and also a synopsis so when you start sending it out to agents or publishers they can get a quick look to see if it's something they want to see more of.
So I've written a book. And now I'm fixing it up. Writing a summary/synopsis of it. Writing a query. Daydreaming about how wonderful it is and how quickly it will sell and make me untold amounts of money. Feeling completely inadequate about the whole process and enjoying it all at the same time.
One more thing. If you've ever wanted to write a book. GO FOR IT! It's hard work, but it sure is fun. And the writing community is so wonderful.