Threesome👯‍♀️🚶🏽‍♂️😈💦

So me n my boyfriend have been together for two years and our anniversary is coming up soon as one of my surprises we having a three some the girl is perfect. I made sure she ain’t have anything made sure she’s comfortable with it etc . I just want to know are there really rules to it or anything else i should ask. Or anything i can do to make it less awkward ? this will be my first one but not my boyfriends. Comment below please