Ask them about themselves!
Yes, it's as simple as that. My grandmother once told me a story about this time she was traveling with my grandfather through Europe, and I believe they were at a business dinner in London and she sat next to one my grandfather's clients or customer, I am not quite sure of the relationship. She wasn't quite sure what to talk to him about, she didn't know him, so smart as she is, she asked: "So, sir, do you have a hobby?" Now let me tell you, they spoke for 2 hours after that about his hobby. After the dinner, this customer/client went to my grandfather and said "Never do I want to see you again without your wife!" All they did was talk about his hobby, I think it was sailing!
So the next time you are stuck, and you aren't quite sure what to talk to the other person about, ask them.. What do you do for fun? I like that approach as opposed to what do you do in life? Seems so text book. I learn the most interesting things about people I barely know. Either they are marathoners, or are very interested in music, or movies, or they waterski or figure skate, or love to organize events.
The other day, I met one of my neighbors, I had never met him before, turns out, he's corporate pilot! How cool is that! He flies people around on their private jets. We ended talking for 30 min approx. I was heading out to my meeting with my committee members for the association/events I am creating for friends helping friends (See It's not what you know but who you know post). He asked me about me and what I was doing and it lead to all sorts of discussions about people we have met, that aren't too crazy, that could help us, to how to network without social media, etc. So interesting! It just so happens that everyone has a little secret passion to them, whether it be fashion, traveling, collecting, or a special sport they do.
Even if their activity isn't very appealing to you, LOOK INTERESTED! You never want to make the other person feel like they are doing something weird, or crazy, or not fun. And once you think that you have gone over all subjects of conversation you wanted to discuss with this person, tell that person that you need to use the washroom (even if you don't), or you need to get a drink, or whatever and move on to the next.
So, passions - Good subject! Works most of the time. Another subject of conversation that I love is traveling. I have been lucky enough to travel quite a bit and I find that talking to someone about their travels is always so interesting. From Australia, to Asia, to Europe, and even places that I haven't visited. I always am interested to know what type of traveling someone has done. Also, other subjects that can used are : that person's background (culture, traditions, etc), technology (ipad, iphone, apple, new gadgets, cameras, etc), and another good one are plans for the weekend! That one always works like a charm, hoping that person actually does have plans, it could be a good 5-10 min conversation which can lead to other subjects mentioned above.
I have also come across certain games that exist that give you conversation ideas like "If you could meet someone dead or alive, who would it be?" "If you had 1 million $ to donate to a charity, which charity?" but seemed that these questions were 1 min type answers. Yes they can be useful in the event of NO CONVERSATION, but I suggest you use your creativity and sometimes you can use things around you when you are really lost. Like if you are at a bar, you can ask them about their favorite drink, if they go out often, whatever. I hope in return they ask about you, and that's what makes the conversation last! Now I know that this might not be an issue for most of you, but who knows maybe this will help you. Too much talking about yourself goes no where, the person loses interest and you become UN-INTERESTING!
So I hope these pointers help - and as my last words of wisdom, if you are a convo pro, well then, I have no wisdom to give you except try asking them about their passions first, it's quite interesting to see people a little off guard.. and for those who aren't pros, be confident, you have tips and advice, use em! You will become that social butterfly in NO TIME!