It’s about flow of information feeling natural. Not a sudden “word from our sponsors” ad break in the story. Or an exposition dump of what a character already knows to cover the writer’s ass from feeling embarrassed.
I will always stand by clear verbal consent is sexy. It can be as subtle as an eyebrow waggle to spelling out what they want where. There needs to be full spectrum of representation. Just let people know beforehand on the cover if you’re walking into dark territory
My go-to for keeping a flow going with characters who care about consent, but don't know each-other's limits yet, is usually just to have the dominant partner pause just before doing an action, deliberately giving the sub time to protest.
That way you can still preserve the spontaneous nature of it