Being more interesting is elementary, my dear Watson!
"Interesting" is in the eye of the beholder. I can talk about the Scala programming language to coworkers and they'd love it. I can't begin to describe how fast, however, my mother's eyes would glaze over. However, I have a few other insights that might help...
The more people that would find you interesting, the more interesting you are. Therefore, you should strive to maximize your return. Look into things that most people would like to learn about or experience. Maybe inventing fun things? Maybe creating stunning and huge works of art?
Robert Frost sure nailed it with the astronauts n' space angle. Don't get caught up with "niche" interests. Talking about carburetors might be interesting to an auto mechanic, but not many others.
Interesting means you know something others don't. You're going to have to scratch pretty deep before you start surprising people. Don't get into anything half-hearted. Truly experience it. Rory Young right now is romping around the Central African Republic, in the name of Quorans For A Cause, trying to up awareness of the horrors of poaching beautiful creatures of the wild, like elephants.
He's getting a ton of footage out there, while running for his life. He has access to information that the average joe has no hope of finding out on his own. Amazing stuff! That's interesting to people!
Interesting means you can do something others can't. Sure few want to flip through Gray's Anatomy, but brain surgery, or grafting skin onto a burn victim, is interesting. You might not like the injury attorney that tears an innocent defendant up in court with incredulous accusations, but it's still interesting. The figure skater who masters the triple lutz would be interesting to onlookers at a skating rink. An archer who can kill a mouse from a treetop is interesting.
Novelty is interesting. The first triple lutz performed at the Olympics I'm sure seemed much more interesting than it is now. But when was the last time someone bungee jumped from the Statue of Liberty? Artists are constantly trying to innovate, and stay interesting. News publications use sensationalism to create a false sense of novelty. You want to be more interesting? Be a trendsetter. Go for crazy fashion.
Carolyn Cho might scold me for saying this, but it doesn't even have to be good fashion! Wear a top from your chinese silk pajamas for a shirt. Or wear a hat made of asbestos. Walk around with a siberian husky and a mexican hairless at the same time. Greet everyone with a haiku!
Also, interesting people don't reveal everything. Few have the ability and willpower to constantly come up with new ways to be interesting. The solution is to hide some of your cards. Be mysterious!
Who is this person? What is his story? What is he looking at? He might tell you something about himself, but are you really satisfied with just that? It's human nature to want to know about the people around them... to want to know where they're coming from, and what they want. Don't tell them. Leave them guessing. If during those moments you do say something, it's incredibly interesting, they can only assume...
That you're the most interesting man in the world.