I don't have a great track record with NaNo. Out of several attempts, I've only "won" once, ha. Yet I'm encouraged by the steady word counts I've churned out this past month, all because I have a detailed outline as guidance. It's possible if I write an outline for my NaNo story, I won't end up 20K behind in the third week like always.
But of course that means choosing a story idea first. The strongest contenders so far are:
Story 1. Dark fantasy (and Red Riding Hood retelling) about a young werewolf named Katydid who, after losing her pack to sickness, travels through an otherworld forest to find Granny Wolf, a divine being who may be able to bring her loved ones back from the dead. If she doesn't first decide to eat Katydid, anyway. There's also a huntress with two wolfhounds after her tail, and a woodsman she keeps running into with a haunted past and a sharp ax.
Story 2. Urban fantasy (and Beauty and Beast retelling) about a sorcerer's daughter, isolated and struggling with a curse, who hires a bodyguard in case the city-wide power struggle between magic factions ever reaches her not-easy-to-find doorstep. (It does.)
Story 3. Science fantasy that expands upon a piece of flash fiction I wrote about an inkwitch trying to make a living off her tattoo spells and the uneasy friendship she develops with a newly-freed android.
All will be written eventually; it's more a matter of picking the best one for NaNo. Story 1 would probably be easiest because of the simple quest structure. Also, the main character likes to talk a lot. That always helps. Yet 2 and 3 are very tantalizing, too. Hmm...