I've done ignoring sessions, it is a fetish. From my experience its literally acting very selfishly, maybe be on your phone, filing your nails, checking emails, doing your makeup etc whilst face sitting him, obviously letting him up for air! Chastise him if he isn't cooperating, just treat him as an object. Don't ask if he is ok, have a safe word though, ask if he wants smothering incorporated.
Good luck x
Also I find a long facesitting session is most comfy if he lays with his arms straight up above his head, I sit on their face facing their feet and hook my ankles under their arms. Hope that makes sense? In this position they can't move.