It's simple, ask them about themselves.
People LOVE talking about themselves.
Brain imaging from a 2012 Harvard study showed that the pleasure centers of people's brains were activated during "self-disclosure" aka talking about their experiences. These are the same pleasure centers that are activated during sex or other "rewards" such as sugar or drugs.
Those who were allowed to share thoughts, versus those who were told to think to themselves, showed even greater reward activity in their brain.
In fact people love talking about themselves so much that subjects in the study were even willing to give up money to do so!
What does this mean for you?
Well if you find it difficult to keep a convo flowing, the short answer is that you can simply ask people questions to keep it going. The other benefit that you get out of it is that people will love talking to you.
Remember people won't always remember what was said in a conversation, but they will definitely remember how they felt when they were conversing with you.
How do you Ask the Right Questions?
When asking people questions, ask open-ended questions rather than "yes or no" questions. A great hack is to "observe" something and then ask about it.
Q: I see you chose the red wine tonight. Why do you prefer red over white?
Q: Do you like to eat cheese with your wine? (Yes or no question)
A: Yes (duh!!)
Q: That's a really nice jacket, what's the story behind it?
A: Oh I actually got it while I was backpacking in Europe, I bought it from this tiny store...
Q: That's a nice jacket. Does it keep you warm?
A: Thanks, yes it does.
**Cue awkward silence**
So the next time you're at a social event, make some friends by asking open-ended questions. You can couple it with the "Yes and Technique" that you learned yesterday to strike the right balance of talking and listening during conversations.