The whole, lovely idea of NaNoWriMo is writing as many words as you can. They don’t have to be the best words, you don’t need to end up with a clean draft. It’s about building a habit and breaking through the fears and anxieties to get words flowing! Because you have to write FAST to write 50,000 words in 30 days.
I have found it very helpful to have a general outline of my story – if I have a list of scenes I know I want to have in the story, it’s easier to jump around and keep writing if I get stuck.