Because I’m writing it, and also talking to cypress-tree about it:
When writing porn, weird is good! Instead of trying to smooth out the awkward bits of doing it in a storage room, or on the sofa, or in the shower, capitalize on them! Horseplay in the shower? Don’t gloss over all that slippery tile—have somebody try to figure out how not to keep sliding away from their partner while they’re trying to get it on.
Don’t ignore the fact that the backrest of the sofa makes it inconvenient for four legs to get around, or that the cushions are giving somebody a kink in their neck; have them roll around on there till one person’s draped over an arm rest, or bracing themselves with hands on the floor, or upside down, for god’s sake! Narrate the adventures of having sex in a supply closet on top of a pile of folders with packs of tiny post-it notes raining down on their heads.
That’s the fun stuff; that’s what makes your sex scene different from all the others and gives your characters the chance to make choices in the scene that express their personalities and proclivities.