My feeling is that it's important to free write, to get it down as fast as I can. Last time I wrote about what I do to not get stuck and to always have something I can write about (since the goal is to get a manuscript of at least 50K words out, not a "perfect" one). Last time was "strategic" ideas, this time more "tactical".
I have pretty much given up capitalization and punctuation this time (I don't necessarily recommend this).
I will be editing later, so I don't worry about anything (spelling, grammar, etc.)
I write down EVERY modifier or descriptor I can think of, even if it's the wrong word, even if it's wordy, even if it's totally convoluted, even if my descriptions contradict each other -- I will edit later
I don't worry about whether it's offensive, obscene, stupid, illogical, etc. -- I'm going to edit later and NO ONE will see it but me
When I slip up I just START THE SENTENCE OVER in mid-sentence, no backing up, no deleting, nothing. I may just try out the same sentence over and over again two, three or more times, type the same prepositional or other phrase over and over again multiple ways or if there was a wrong word back a line or two I just type it (more) correctly right where I'm at and carry on. Just like I were talking.
When I get a new idea for a different scene or whatever, I just hit Return a couple of times and start typing. I may do that again a paragraph later and go back to what I was on before or go to something else. You can also just hold down the Equals sign to make a score through your manuscript to highlight the complete change of direction for when you edit later.
I put brackets [ ] in for editorial notes for later, e.g., [Jesse should do this instead of Claire] or [strike this?] etc.
I don't spend time worrying about getting my characters and places names right, at most just put [wrong name?], [that ninja girl here?] or just [?]. There WILL BE INCONSISTENCIES and I will sort them out later, and I do merge characters [next point]
I don't worry about chronology, logic, narrative inconsistencies -- I will sort those out in editing. I just try to write cool scenes and ideas and conversations about interesting and compelling stuff so I have something to pick from later when I'm editing. I expect that important (and unimportant) characters will do inconsistent stuff and I will decide what they are as a character later, based on what is most appealing when I have the manuscript done.
I don't worry about outlines or preconceived plots. That comes out later based on what worked or was worth keeping once my first draft is written.
For minor characters (or even actions I'm not sure I want my major character to do), I'll just grab a new character, make them up on the spot, with the idea that they may be merged into another character or a main character will take over that scene, that action in the editing process.
I will sometimes go off on a complete tangent and write something that I KNOW is inconsistent with any vision I have for the story, or even sometimes completely off topic (this could turn into a dream sequence or vignette later), if that's what helps me to keep writing along at a given moment.
We will have an ongoing editing workshop that will probably continue to meet twice a week after NaNo and go on until next Nano. Feel free to join.