How to be a better offline conversationalist?
1) Practice by talking to people
2) Listen more than talk. Pay attention to what others say. Most people are more interested in talking than listening. Obliging them is not difficult.
3) Don't stress too much over the "finding common interests" thing. That fails if you have no common interests, and being absolutely fascinated by someone talk about something you know nothing about will often engage them just as well. Plus by listening you expand your own knowledge pool and increase the number of things you know about and can talk about. What one person tells you about while you listen one day might be something you cn talk about with someone else the next.
3) If you ever find yourself completely stumped for a response, repeat the trailing few words of what they just said and turn it into a question. Example: "I love underwater basket weaving and my lifelong dream is to get rhinoplasty." --> "You want to get rhinoplasty?"
4) Sing to yourself often in private. The voice is like a muscle. The more your work it the stronger it gets. Having a
pleasing voice will make you more pleasant to talk to regardless of what you say.
5) (Advanced) Mimic their language, body language and energy level. If someone greets you with "hello" responding with "hello" will tend to get a better result than responding with "sup, dude." Examine their word choice. If they're talking about their
children, then talk to them about their
children, not their kids. If someone is speaking really fast and with enthusiasm and cheer, responding slowly and deliberately might bore them. If they're speaking slowly and deliberately, speaking fast and with enthusiasm might tend to make them feel drained. Be aware of your partner's mode of communication. Match them. Or at least meet them halfway.