I think topic of conversation is not important. You just need to be relax and honest.

It's not easy to talk to strangers because most people don't have enough courage to be the first one to start talking - even if both sides really want to. Especially when it comes to the opposite sex. Girls are too shy to start talking to guys and if the guy starts talking first the girl will think the guy is hitting on her. A lot of potential friendships and relationships are lost because of this. There are so many people in the world that lonliness shouldn't be an issue, but this phenomenon is the cause of it.

wanna = want to

leave all protocols and start conversation with heart you will found mutual understanding and may be you can find our a best friends.. no one knows how we meet strangers and where but they may become an important part in life.. become a bond of friendship :)

I agree with hedji.  In fact, I reckon the most difficult part is to get mingle with the strangers.  I wanna know how to talk to a stranger.