Conversations aren't about transmitting information. They are about two people bonding and this is done by sharing information, yes, but also feelings, views on the world and so on.. It's about making all of your personality shine through and helping the other person let their personality show.
I used to come across as a really interesting person when I had something smart to say, but I turned into a clam when I didn't have anything. What I did was I saw conversation mainly as a means of exchanging information. As a hardcore nerd I of course had a slight touch of Asperger syndrom and found it meaningless to just talk to people. Then I realised being social is a skill like any other and I decided to get good at it. Just go out and be social! Call up your close friends just to see if you can get a conversation going with nothing in particular to say. Talk to people all the time. Say something to the cashier, the person next to you in the elevator, next to you on the bus, about the weather or whatever. Ask someone about the time and follow it up with a little joke. Anything, no matter how lame, is better than nothing at all.