What not to do

If a girl is alone happily nibbling on her sushi while waiting for the train, don't try to pick her up.  

Don't talk to her for thirty minutes straight when she is clearly more interested in her food than patronising conversation.

Don't tell her about how bored you get in the suburbs and how you'd like company.

*shudder*

And don't ask her for her number.

Oh, and please don't try to offer her yours either.