This will be my fourth year doing Yuletide, and every year, I am more and more amazed at what the participants in this challenge can pull off. I've never had a disappointing Yuletide morning, no matter how closely my writer followed my prompt or how much they took it off into their own fantastic directions. My suggestions are just that: suggestions. I would rather receive a story that someone was passionate about than one written out of slavish adherence to specifications. Write whatever you need to write to have a good Yuletide.
That said, if you're LOOKING for some guidance: I'm agnostic regarding femmeslash, slash, gen, and het. I'm very into fanworks that interrogate the text, that poke at it and extrapolate and build in new details that may or may not be comfortable to read about. I also like banter, science, history, and literary references. If you have any more questions about my preferences generally, please consult my dear internet bring me a pony tag, which contains my previous fannish challenge letters (including, uh, the one that I apparently didn't write last year. Whoops).
On to the fandoms!
(Fandoms to come.)