Conversation is like playing tennis, except that you want to keep it going by actually asking thoughtful questions and making interesting comments. Awkwardness usually comes from realizing that you aren't very deep - so read a book and watch the news occasionally (no one cares when Justin Beaver's next breakdown is gonna happen though).
I get this a lot.. Dude seriously don't be afraid to talk about anything, being spontaneous is attractive and you don't have to give a one shit about trying to impress anybody. When things get silent and awkward, that's the best part for me when I'm out with a girl. I can literally change the subject to anything and sometimes even lead to a kiss. Get out of your head and live in the moment. When you have monkey chatter in your head, that's when you're already messing up. Be confident cause you have to lead and let them follow. That's how you get that girl. And don't ask to many questions, that'll just make her feel like she's being interrogated. Good luck bro.(: