Stay casual .. talk about what's happening just there and then. What they did that day. After you get a connection trough smalltalk you can start talking about more personal stuff.
As for topics.. Music and travelling works very well for me. Most girls find especially travelling fascinating. Oh .. and ask open ended questions as Sleepyjack said. If they give you a short answer such as "I don't know", don't say anything. Just look at them and wait for more. May feel a bit wierd, but you'll kinda make them open up a bit more.
Oh, and stay off car and football talk :P That's a crash and burn ..
