My boyfriend and I were recently discussing our fetishes and fantasies and I came out to him that I am bisexual and he came out that he's always wanted to have a mff threesome. I have never had one and wasn't even sure how to do it (positioning etc.). I've looked it up online and found some positions I like and some great advice such as setting boundaries ahead of time ( my rules are, pay more attention to me than her and no penetration with her). The main issue is how to find another person. We met a girl at a video game store that we both think is pretty cute, so we are going to try to get to know her and hope for the best. Another possibility is a mutual friend of ours. She's bisexual and I've had a crush on her for a while. Austin (my bf) thinks she's beautiful as well. She's always asking me about my sex life with Austin and suggesting things for he and I to do. She's very kinky. I told her we were going to try to have a threesome and she asked me to tell her how it goes when we find the right girl. I'd like to ask her, but she's a co-worker. In fact, I am a cashier, my bf works on the lot there, and she's a head cashier. That would make it so wonderfully kinky if things go right, but could definitely be an issue if things go wrong. However, since she is a good friend, I trust her more than I would someone we don't know as well (important especially for things like stds) and she has a very serious boyfriend that she is very much in love with so I'm really worried about her trying to take mine since she's happy with the one she has.
I should also add that I know threesomes can lead to jealousy and awkwardness, etc. However, we are in a point in our relationship when we are very much in love and I believe that we are ready and that this could be a positive thing for our relationship as we explore our sexual side.
1. How do we find the right one?
2. How do we ask when we find one we like?
3. Any additional advice about threesomes (other than "don't do it" and "you're boyfriend is a pervert for wanting two women")?