Let's see. Last year I learned that I could go into a novel with no clue what would happen in it, & it would be okay. I also learned that I could do a pretty steady pace of 2K a day if I actually BIC'd like I was supposed to, & make 50K in less than a month.
This year I learned:
I can do about 7K in one day, but I have to spend several hours in the Borders cafe to get most of it done.
NaNo-ing w/ friends is okay... as long as you aren't hanging out in person. Once someone's around to distract you, they will.
Sometimes what the story needs to really come together is to take a male character & make him female instead.
Going in with an idea of where the novel is going is great... but being flexible with what's going on is also important.
That
Dr. Who is awesome! (sorry, we watched it a lot this month, & it gave me an idea for a part of the finale at one point)
That I can set my fantasy novels in the "real world," as long as it's part of the real world I'm familiar with (& even then, I'm typing "look up a lighthouse near here " 'cuz I'm going there for Christmas).
If I aim for 50K, I'll probably end up w/ a 60K novel.
If I'm at 42K & nearing the finale, I'll probably still be okay (second year in a row that I started freaking out in the 40Ks because I didn't think I had enough story).
Sometimes all a story needs for me to get over the "this sucks" doldrums is a goal of 50K/30 days. I mean, I started this novel back in May ('cuz I was working on it on the way to a wedding), & abandoned it shortly after, having written 2 chapters (& 3 separated paragraphs 'cuz I kept restarting chapter 3). Then in September I was talking to a friend about the WIPs that I had floating around & about maybe finishing one for NaNo, & as I described it, she thought it sounded good, & I realized that of all my WIP plotlines, it really was the best. And once late October came around, I was really excited about it.
That a quickly written novel seems to also have its soundtrack quickly developed... but always with one extra song than a CD has room for.
A novel I wrote in a month is probably going to need a lot of editing... but really no more than the one I took a year & a quarter to write. With the exception with some grammar problems I'll get in the first pass of editing (probably), the problems I have with writing (especially description) are always there whether I stress about them as I go or after I'm done. As long as the plot is strong, I'm okay with it. And really, with only a month to write, I have less time to take side trips through Background Land or whatever else I felt like adding for fun, even if it just barely furthers the plot.
But on the slightly more negative side, I will say that while I love both sets of my NaNo characters dearly, I know I'm much less attached to them than the ones I spent over a year on. Last year, I killed off my favorite character of that novel without a second thought. There are moments where I really get involved & feel for my characters, but it's not the same as my other novel. I mean, I did horrible stuff to my MC in that one's finale & I walked around in a daze for a full day. I was even meaner to my MC in this WIP, but I never felt the same heartbreak I did for my non-NaNo MC (well, except when I listen to the soundtrack. Music does that to me). I was excited by what happened in both finales, but there's still a big difference.