When I was 16 and living in a foreign country, I would talk to my peers by asking them open-ended questions. These are questions you cannot answer with "yes" or "no". This lets the other person talk more, and gives you more things to ask questions about. This is good for conversations over lunch or at a party where you have some time to talk. Some examples are:
What do you do for fun? What do you do on weekends? What is the last thing you did with a group of friends? When is the last time you traveled somewhere as a family?
What is your family like? What is your relationship with your sister like? Are your parents strict or lenient? Have you ever gotten in trouble?
What are you studying in school? What do you hope to study later on?
What does your family do for [Christmas/Easter/Halloween/some holiday]? How do you celebrate in [country name]?
Or if you are writing letters back and forth, it is a good idea to offer a little piece of yourself, and then ask them questions that are similar. An example would be: "I just read a book called [BookName] and it was about [topic]. It had an effect on me. It made me [think about something different / remember some funny story / understand some new idea]. Have you read any books or seen any movies lately that you have been thinking about afterwards?"
If you are just seeing people for a short time, like waiting in line for coffee, or in an elevator, you can start up a very short question/answer about an easy topic. You could say "do you have any big plans for the next weekend?" This usually gets a bit more of an answer than the simple "How are you?"