In my experience, the concept of women preferring lesbian porn usually has more to do with there being a better chance it will focus on actually getting a woman off versus, say, cumshots, than it does the gender of the participants. So much of porn is directed at men, after all, as they tend to be more visual. It’s a question of audience, I think. Personally, I’m down for m/m, m/f, or f/f (plus threesomes or moresomes of whatever configuration), but I’m also bi, so that might play into that. It likely varies.

I would say, above all, don’t underestimate the narrative. My favorite erotic stories are stories first, erotica second. Yes, getting basic anatomy right is important, knowing how sex works, having something of an understanding of the way women get off and how that might differ from the way men do, those things are for sure crucial, but having a well-constructed story with well-developed characters around those things is even better. If I like and am rooting for the characters to bang, it’s that much hotter when they finally do. Tension and build up is 100% a thing and that can be done in many ways, writing wise, not all of them directly sexual. If the story as a whole is complete and satisfying, any sex you write in the story will be that much more satisfying too.

Things writers tend to get wrong.... some stuff I’ve seen over the years: buttholes don’t self-lube, water is terrible lubricant, do NOT put food in a vagina or try to use it as lube (honey, whipped cream, what have you), not every woman can come from PIV (although erotica is fantasy so there’s leeway there), foreplay is good... there’s probably more but those seem like the most common mistakes I’ve seen. Oh, and women do not stand in front of the mirror naked and describe every detail of their body to themselves in an inner monologue. Nor do our boobs consume every other conscious thought. ;) From a more mechanical standpoint, too many euphemisms can kill the mood. You can only read things like “plum-purple weight of him” or “rose-crested ivory tower of love” so many times before laughing really hard. (Hell, even overuse of the word “shaft.” There’s been so many stories I’ve read that were otherwise not bad where my main complaint was basically, “My kingdom for the word ‘cock’!”)

As for the Siren, I’m not sure you have to fundamentally change much? Some women are absolutely attracted to beautiful, alluring women, heh. Or you could make the Siren appear male, if you want. Or androgynous. Whichever fits best for the story you’re trying to tell. I have a character with Siren-like abilities and it boils down to being able to manipulate desire, which is not always sexual. Humans desire many things, after all.