First MMF

We're a bi couple who enjoy a sort of swinging life. I am new to having a bi guy, but very excited. No, not all bi people enjoy threesomes. That's not how it works. On that note...we will be meeting a male playmate for the first time. My sweetie has never had a woman who wanted to watch or participate with him and another guy. Now he does. We're so excited!! Anyone ever do this? Any tips for a first-timer? (I've had FFM).