One of the main purposes of Nanowrimo is to encourage you to get words down on a page and at the end of 30 days to have accomplished at least 50,000 words of your novel. Remember, however, that these words do not have to be perfect. This is your opportunity to write your first draft without worrying too much about whether you've selected an ideal word or sentence to portray what you want to get across.
You have to be able to switch off your inner editor (which is easier said than done) and focus instead on writing down the words. As Neil Gaiman says:
“This is how you do it: you sit down at the keyboard and you put one word after another until its done. It's that easy, and that hard.”
If you let your editor get involved in the Nano process, this can be a real distraction from writing. So in this instance you have to practice letting go. It really is quantity over quality. But how can you let go of your editor if you're always used to him or her looking over your shoulder. Like a lot of things, it can be as simple as being aware of it. Once you are aware that your editor is present, tell him or her to go away. Advise that they're not needed at this point, but come December, they will be welcome once more. During November, you may even wish to wear a band on your wrist. Each time your editor appears, ping the band to remind you to let go. Or perhaps put a note on your screen or in your notebook that reads: 'Editor - be gone' or whatever appeals to you.
When I successfully completed Nanowrimo back in 2011, my writing was all over the place. There were chapters missing, lots of tell, not show and the final chapter didn't have an ending. But I certainly had fun along the way. I wrote scenes that I enjoyed writing and introduced random characters who aren't in the current version of my novel and ate cakes and drank coffee with other writers at least once a week. And when I reached my target on day 30, writing 10,000 words in the last two days, and the final chapter wasn't finished, I didn't care. I submitted my words and printed off my certificate - proud of what I'd achieved.
So simply throw yourself into Nano. Write without that critical voice reading over your shoulder, write it down, rather than being worried about getting it right. Here's your opportunity to write with absolute abandon and most importantly enjoy it and have some fun along the way.