How do you write?

At the beginning of the year, I got a daily calendar produced by Writer’s Digest. This weekend’s quote was:

“I suggest that writers come up with their one-sentence pitch first, then write their synopsis, then write their book. Almost no one works like that naturally, but once writers make the switch to that process, their writing tends to be cleaner and more focused, and, in my experience, it has better luck in the marketplace.” ~ Jenny Herrera, David Black Agency

I don’t write like the above. I’ve tried, honestly, but things tend to veer off my synopsis as I go along. I learn my characters more intimately as I write about them, and they share things I didn’t know about their personality, motivation, backstory…
I usually start with at least one character and a conflict. When I wrote “One Love for Liv” during NaNoWriMo, I had the three main characters, the conflict and I used writing prompts to generate potential scene cards. Liv had a tendency to veer into the very silly (Frank, in particular, was one of my favorite all time secondary characters). It helped to keep moving forward to have the prompts and scene cards, and I’ve done the same thing for other stories.
I also tend to know how the story will end. IMHO, if you know the beginning and you know the end it’s like taking a trip…you need to get from point A to point B, but sometimes you take unexpected side roads. You still get there, but those little unexpected trips frequently make the journey richer.
How do you write?