What's your style, and why?

Things are crazy at the moment, so I'm just going to drop in and ask something quickly: What's your plot-preparation style?

The reason I ask, to be honest, is we are getting into "plotting vs. pantsing" in my creative fiction class, and I'm just always curious how other folks go about their writing. I've read plenty of accounts of authors who can't start a book unless they know how it ends and what most of the major twists and turns will be. Then there are those who can't plan it out ahead of time because it is so boring to try and write after that, and they go on to a more engaging and NEW story to write.

Me, I'm actually trying something new. My first manuscript was one that I did as a half-and-half. I started with a rough chapter-by-chapter outline (really rough, and I rewrote--or at least re-ordered--the first third of the book after I had written it). Thing is, I was so excited about the story that I dove in right after finishing the rough outline.

Boy did that screw me. Granted, it was my first shot at a novel-length manuscript, but even for that it stunk. I've since gone through all the rewrites, and I'm pretty happy with it even if it never gets published. Maybe someday if I hit it big, I'll put it on my web site as a freebie or something, who knows. Point is, I am not a guy who can just dive in and go. I gotta know:

1) where I'm headed
2) how I plan to get there, and
3) if that plan is a sound one.

Yep, missed step 3 that first time....

So now I'm trying the Alexandra Sokoloff Index Card Method, and we'll see how it goes. Once again I'm really jazzed to get into the story, but this time I'm gonna make sure my plan is well-thought-out beforehand.

So what about you? Do you plot away the days before writing, or do you jump on the chair, strap in, hold on, and fly that story by the seat of your pants?