Oh hey! You're the guy who made webm related, nice.
Honestly, as long as it doesn't go into the hardcore fetishes like vore, gore, piss/scat, etc., it's fine. As far as poses and such, a different anon could probably come up with something a little more creative than me, but I suppose a human guy fucking a significantly larger female wyvern from behind wouldn't be bad. Maybe a little followup where she's laying his eggs afterwards? Just a thought.