Like any conversation, you need a good ice breaker.
When talking with people online, I generally start with something outlandish and overly awkward.... The bar is much higher, the ice much colder online. Gotta whip out the gas-powered jackhammer to break it.

I feel that you can get more unadulterated true insight into the person's mind online, but in person, you get the person they present them self to be (Which, really is who they are... You are who you pretend to be.) So both have their strengths. I think you can get to know a person's motivations and philosophy faster online, but you can never truly "know" someone unless you've spent time with them.