Don't be lead astray ;-)

Do you know how to write a novel?
- One word at a time.

To be able to actually get the writing job done in 30 days, you have to be really careful not to allow anything lead you astray...

- reading what you have written
An absolute no-no. If you do, you will start questioning yourself, perhaps editing, rewriting... and then you are lost.

- rewriting
It's good as it is. Come on, it's not the final manuscript, it's your FIRST DRAFT! Write, don't rewrite. You have the 50.000 words goal to reach. You can rewrite it in December. Or not rewrite at all, just chuck it. But now, write.

- editing
You know it can be said "better". Don't try to say it better, at least not right now. Besides, 9 times out of ten, your first way is the best after all :-D

- new ideas
Oh, the shiny new ideas, thousand times better than anything you have written so far, and especially the crap you are trying to write right now.
Just jot it down in your writing journal, and get back to work, which is writing THIS idea.
Even if the idea isn't shiny and better, but just a good idea, write it into your writing journal, to be used in the future.
Now, if you get new ideas all the time, and you would use more time writing down your ideas in the writing journal than actually writing, it's time to let them go. Let them pass your mind on their way to someone else who has more time or less ideas. You have enough, you can let a couple go. You really need to DO something with the ones you already have.
Also, the flow of ideas will not stop. Even if the fear of failure or success or what ever makes you THINK you have no ideas, the second you are not afraid anymore, the ideas come back.

- forgetting details
Suddenly you don't remember what color eyes Harry had.
Doesn't matter. Put it in brackets, make a mark in the margin, write in your writing notes to check the color of Harry's eyes. Don't stop writing to check it. You can do that after you have done writing.

- background research
You really want to write a magnificent fencing scene, but know nothing about fencing.
Doesn't matter. Write what you know, make a note in your writing notes, watch some movies with nice fencing and read a couple books about fencing and swords, so that you will know WHEN it's time to edit the draft. Don't do it when you are writing.
It's even quite ok to add a big blob into your draft, and write "here fencing scene", and then act as if you actually just wrote it.

- the life
This is something that cannot be avoided. Of course, you can get a butler who takes care of every phone call, visitor and your mother, or go to a tent in the middle of a forest somewhere, and sit there with both ear plugs and earmuffs, but I'm sure SOMETHING will happen - like your tent catches fire or a moose runs over it or something.
Leave yourself a short note and leave the last sentence unfinished. Might be that you won't remember anyway what you were about to write, but, I doubt it will be a truly big loss for the world literature. Just get back in the flow and keep writing.

- procrastination
There really isn't much else to do about this, but SIT DOWN AND WRITE, DARN IT!
You can procrastinate all you want after you have written your daily words. But only till next day.

- perfectionism
At one point of the writing you realize that it's the worst thing you have ever written, hey, it's the worst thing written in the history of mankind, and probably nothing written in the future will be as bad.
Doesn't matter. Keep writing.
And keep the text. If it IS the worst thing ever written, at least it will be fun to read :-D

- fear
At some point you realize that what you are writing might actually work... it might actually not be that bad, and it might become a real book.
Doesn't matter. Keep writing.

- normality
What you write is totally uninteresting, boring, old, said already thousand times, by thousand different people, your POV is the usual one, and so on and so forth. Nothing new, exiting and interesting here, thank you.
Guess what? A Finnish poet wrote a very short poet, which I happen to love. "It has already been said, but I say it again, to you."
There's hundreds of love songs, and all of them are practically the repeat of "I love you". You probably like some of them, don't like most of them, absolutely love a couple... it's the same with literature. No-one has ever written what you are writing right now. May be that it has already been said, thousand times, but there is someone out there, who needs to hear it from you to get it.
Keep on writing.

time
- There just isn't enough of that stuff.
Most people already waste time here and there for nothing. Television and internet are two big villains here. You can collect minutes by walking a bit faster, showering a little quicker, getting up when you wake up... Have a day in a week when you plan the food for the whole week, cook big portions and freeze them in tv-dinners, and shop everything you need at one go. Clean every day for 15 minutes, and you don't ever need to spend hours in cleaning. Learn to use your human network and delegate jobs. Don't take upon yourself jobs you don't need to do. Study some time managing and organizing. Declutter your home, your life and your mind.
And PRIORITIZE.
You don't need to write EVERYTHING there is to write. Just this draft. Just the daily words.
If you REALLY want to write, you find the time for it.

33 rules for writing fiction