Don't force or coerce her into it, nor should you be. Some women agree just to make their partner happy and aren't able to get into it... or bail outright. You both have to really want to do it, agree on a bull together and vet him.
Glad to hear you're not rushing into it and that it remains a open discussion with her. The more you communicate your expectations with each other in advance the more comfortable you'll feel and the better the experience will be. Don't let fantasies/porno get you all hyped up--this is a stranger who's going to fuck your wife... which is definitely part of the appeal. I'm just saying.
Communicate with the bull you choose. Make sure he knows your limits as a couple(e.g. no kissing, no cunnilingus, no hair pulling, biting, bondage, spanking, slapping, commentary, drugs, "dirty talk", etc.), though don't hit him with too long a list. "Just fuck my wife" usually worked fine for me.
Make sure you know his limits, too: e.g. it's always a surprise when a husband says he's just going to watch, then whips it out and starts to jerk when he gets turned on. I like to know he's is going to stay off the bed in a chair and just watch. Cameras? In my day they were mostly polaroids, but only I was allowed to operate the camera to take close-up fuck/body shots, no faces, otherwise no cameras.
Where will you do it? In your bed at home? Some couples prefer the neutrality of a hotel room.
Hope this helps.
