No, I've been doing NaNo's for years now. I actually joined up during either the first or second WriMo, but I didn't gather the discipline to just write and write until I dropped for years later. I even took a hiatus because I'd failed so much.
If no, how many times have you done it and have you won?
Hmmm, technically I've won several times, as in "I made my word count"... I have not, however, won because I had something finished and ready to edit and rework.
If no, what is the best tip you can give to a first-time NaNo'er?
1) Always plan for things to go wrong...
2) Try to get a few extra words in each day (the daily average needed is 1667 to make the 50K, but if you aim for 2000 or even 2500 you'll have a buffer for those days you don't feel good or you need to run errands)
3) Always let the people you're involved with know about your goal so they don't unintentionally derail any plans you've made for writing time. Writing that many words can be daunting, and it IS time consuming--make sure your friends and loved one are one your team.
How much preparation do you plan to do before November 1st?
This is actually my first year of planning... I'm even involved in a FastDraft (Plotdrafting) so I can do more than just get my word count in--I can also write the whole story. Usually I start writing ideas on November 1st and start actually writing my story by the 2nd or 3rd.
Got anything you'd like to tell us about this years project?
It's fan fiction this time. I mean, I guess they all are to a degree. My initial writing world and ideas are all derivatives of other people's ideas and the world around me. Though I bet I'm one of the rare few who'd write a fan fiction about Jayce and the Wheeled Warriors.
Anything else you'd like to share?
Not sure what would help... Most people actually know how they want to write and what they want to write as soon as they start considering the idea of writing. They may not know it, but they do.... And that's okay. To write and offer a piece of one's soul to the world for review, analysis and discussion is an amazingly strong act.