First, a great thank you for doing Ladystuck. I know it can be rough trying to get into someone's head and write something they'll like while enjoying the writing yourself. I want you to have fun and be in your pleasure zone/comfort area as much as possible.
Goodness, I adore the trolls. I really do. I know that makes me sound like a NuFan but I can read about humans in many more places. What I especially love about Homestuck is that there's a giant world but I can read it in such a Jungian archetypical way. I find that fascinating. Details are symbols and it's so full of symbols and I adore that.
I find their solitary natures fascinating. They are winners from their youth and now alone most of the time, devoted in many instances to their defined but isolated existences. And yet, it's not all serious. (Even Kanaya has her moments, especially early, when she's got her frivolous drinker books.)
Also huzzah for their implied inherent pansexuality.
Things I love:
Teaching, especially the experienced versus the innocent.
Blackrom is so fascinating. Got to have both sides, though.
I love scenery and costumes and Weird Things and ritual, things that Must Be Done for undefined reasons. I love to see the powerful crash, but I also love to see the subtle achieve power. I adore it when people notice something they never did before, see a tiny corner, discover something, get in over their heads...
Things that really take me out of enjoyable reading: human slang for troll bodyparts, and wonky grammar. I'm sorry, it's just jarring to me.
If you do write erotic-type content (Fade to black or get in and get soaked, it's all good):
I don't have a set headcanon for troll sexybits, just don't use human terms. It just seems weird to me.
I enjoy some of the 'grey area' kinks, like questionable consent or non-con, sharp things, and blood play. I enjoy both physical and psychological aspects of D/s, but not lifestyle D/s fic. I have a massive religion/ritual kink, as you may guess from my handle.
Specific things I'm not into: vore, fur, feces, vomit. (Also, it's unlikely to come up in Homestuck, but pregnancy fic, no thank you, and anything identifiably 'medical kink' brings me right out, what with my IRL profession.)
Thank you again - have fun.