Definitely work the conversation into things you know that the other person likes, at least to start.
E. g. you meet someone walking their dog (I use this example constantly). Ask - "What kind of dog is that?" "Is he (or she) friendly?" "What is the dog's name?" That sort of thing. Not the third degree. Just a few quick things and then move on. I approach total strangers this way, and it helps with shyness. Plus I pet a lot of dogs this way.
Someone has a baby stroller. You're walking by. You can always say, "Oh, what a cute baby!" Mothers, fathers, nannies, they appreciate that. It's a nice thing to say. Anything more can get creepy. Recognize that asking the baby's name is a very different dynamic from asking a dog's name.
You see someone from class. "Did you get the assignment?" "Are you ready for the test?" "Do you have good notes from yesterday?" "What do you think of our teacher?" These are areas where you know you have something in common with the person.
You see someone from the football team at your school. "I saw the game the other day. You guys were great!" "Whew! It's a hot day for practice."
I realize these sound vapid. And they aren't exactly full-on intellectual or anything. But you can't really go zero to sixty.
I am suggesting talking to strangers because, believe it or not, there's actually less invested in that. If you screw up, what's gonna happen? You're a nice 16 year old girl. They are not going to run screaming from you because you asked their dog's name.
The more you talk to people, the easier it is to talk to people. This is an acquired skill and it takes some practice.