Whether you 'won' NaNo or not, chances are you were able to get a good amount of words written for your new novel if you participated. But now you are left with an even larger challenge. The huge push to get so many words out in such a short time can often result in a creative burnout at the end. But that's okay, because now that you are finished with your novel, it's time to take a step back and let it sit.
Finishing a novel is a huge accomplishment, one you should celebrate by setting it aside and letting it steep. Thoughts and ideas will come to you during this time. It's good to jot them down, but resist the urge to jump back in and edit. Let it sit so you can return to it with fresh eyes and a fresh perspective. The amount of time you let it sit completely depends on you, but I recommend at least a week, and up to a month. I always try to let mine sit for two weeks.
When you return to edit it, do so with the same dedication that you wrote the first draft. Don't be in a rush, especially if it was a #NaNo novel! Whatever your editing process is, be sure to do a thorough job before you submit it. More on editing next time.