Talking About Nothing, On Purpose
Small talk has a bad reputation. Many learners think it is a waste of time, a pile of empty sentences about weather and traffic. But in English-speaking cultures, small talk is not really about information. It is a signal that says, "I see you, and I am friendly." Skipping it can make you seem cold, even when your grammar is perfect.
The safest topics are the ones you and the other person are already sharing. The room you are standing in, the event you are both attending, the long line you are both waiting in. Commenting on a shared situation feels natural because it needs no background knowledge. "This line is moving faster than I expected" is a complete opening, and it costs you nothing if the other person does not want to talk.
The second rule is to avoid questions that can be answered with one word. "Do you like this conference?" invites a simple yes. "What made you decide to come to this conference?" invites a story. Open questions do the hard work for you, because the other person keeps the conversation alive while you simply listen and react.
When you do react, repeat a small piece of what you just heard. If someone says they moved here from Osaka last year, you can say, "Osaka! What surprised you most when you arrived?" This technique proves you were listening, and it saves you from inventing a brand new topic every twenty seconds.
Finally, learn to leave. A conversation that never ends becomes uncomfortable for everyone. A short, warm closing such as "It was really nice talking to you, I should go find my seat" gives both people permission to walk away. Ending well is what makes the next conversation easy to start.