You either have a reason to believe she'd be interested in talking to you (this could be anything from eye contact to something suggesting common interest, or a million other things that normal people perceive on the daily) or you don't.
If you don't find anything suggesting that she'd be up for a convo, don't try to start one, especially on the street with a total stranger, and especially if you only want to start said convo because you think she's attractive.
XI Wiki


