It depends in which country you are and sometimes, even in which part of the country, because different cultures have different views. I take it you don't mean in the business relationship sense, as in at work?
If you see a certain girl every day, say at the bus stop, it may be permissible to comment on the weather, although in some countries, even that would be frowned upon. If she does not turn away or ignore you, then you could talk a little about yourself, such as, "I have to be in work at 8.00am every day, so I hope this bus isn't late". If she is interested, then she should reciprocate with similar information about herself. If she says something like, "yes", or "no", or doesn't seem interested, then you need to forget it. If she gives you a similar amount of information about herself, then you should be able to take it a little further from there.
Useful topics of conversation might be T.V., work-related topics, the weather (if you're in the UK!) the local landscape or cityscape, behaviour of drivers on the roads, the difficulty of travel on public transport, etc.