What advice would you have for a boyfriend who's never gone down on me before (cis-female) and is somewhat clumsy in the bedroom? I don't want the moment to be ruined by having to explain it all in the moment.
Just tell him to do what feels natural to do. If he does something you don't like, just guide his head elsewhere. My partner hadn't gone down on anyone before either, but with time he learned and has gotten VERY good.