approaching stranger

[riggs]

I was inside a coffee shop a few days ago when a woman took a seat, facing me, outside. She was by herself, with a book and I assumed single. She was engrossed in her book but was also looking around at passersby. She hadn't noticed me when I caught her eye and smiled, which she returned. A few minutes later she glanced my way and I smiled again, which she also returned. I knew I had to approach her and eventually went outside, made a comment about her book and I asked if I could join her. She said sure and I sat down. For some reason I felt like a creep. She was willing to see what I was about but all I did was ramble for a few minutes asking her questions when she abruptly left, saying she was meeting someone. What is the success rate on approaching like that? It might have gone better had I had been able to start a conversation before asking if I could join her.