Just keep in mind a few things:
1. Someone can't fight if they can't breathe. Punch him in the neck. Front of the neck won't kill him but will make him think he's dying. Side of the neck will knock him out.
https://www.youtube.com/watch?v=DcaOr1TBA1w
2. Balls. Kick. It's hard for him to fight when he's puking.