>>648497755Make sure you're both comfortable with it, let her pick the other chick out if possible so that she doesn't feel threatened or simply not attracted to her.
I was told it's best to find someone you don't know rather than a friend since otherwise it becomes awkward that one or both of you know the third person and feels might get in the way.
I've debated having threesomes but ultimately it would ultimately have to be about my pleasure and I'm not willing to put my partner through that (and visa versa if it was about their pleasure and not mine)