I think it's a good idea - if the pressure doesn't make you feel stressed, or a failure if you miss the targets. Try to keep it as a fun thing, and not another chore.
Here are my tips for keeping on writing:
1. Start with at least 3 major plot turns. I did a class last week where everybody got 3 at random and had to outline a novel length plot. Examples of the plot points were Someone reveals something, someone discovers something and someone succeeds at something. Whatever it is, it has to mean a major change for the characters.
2. Use names well. Jane is not as good as Mary Jane, which in turn isn't as good as Miss Mary Jane. Remember you're going for word count targets. Ditto place names. Kingston on Thames, anyone?
3. Don't waste any time looking up words in a dictionary or thesaurus. The same goes for metaphors and similes. Oh, and cliches are fine. Use the first thing that comes into your head - it's about quantity, not quality.
4. Description of what people are wearing can add a couple of hundred words easily. Also describe locations in loving detail.
5. Plot ninja is a new term for me, but it covers an event that acts like the literary equivalent of a ninja leaping out of a cupboard - the story spins into a new direction. Get a store of plot ninjas before you start and write them out on cards. Then, when you get stuck, pick one at random. Examples might include: an unexpected letter turns up, the phone rings with an unwelcome message, someone turns up at the door, the electricity fails, the car breaks down. When in doubt, introduce a new character (and a whole new set of clothes/personal habits/quirks to write about).
6. Remember that dialogue can be as aimless as it often is in real life. Long rambling conversations that go no where are just fine for NaNoWriMo.
The overall idea is to release you from your inner editor and critic and just get writing. At the end of the month you may have 50,000 words of tripe, but there will be some nuggets there - there may even be a story. Use the month for having fun and giving it a go and seeing what happens. And remember, whatever you write can always be re-written later on.