Obviously in this case I took the initiative. Quick recap: Tuesday, I asked her out. She said yes. Next day she called me, said no. Thursday we agreed to forget the whole thing. Today she called me and said she wanted to go after all.
Yes, I took the initiative, but when she said no I stopped. Because that's the kind of guy I am.
That said, I am totally passive in many ways, by no means limited to flirting. However, when sufficiently motivated I can usually get what I want. My life tends to work out alright, just not quite as well as I'd like.