As a disclaimer, I have to say this is based off of my own personal experience, the human condition and a few books and many internet articles I have read.
1. Talk to them, don’t just stare at them
Believe it or not, introverts do like conversation. They just often like to avoid sidewalk talk. Not saying it is not needed: for example, if you are interested in going on a date with this introvert, don’t just jump straight to asking them out. They need some time to read who you are and warm up to you. Don’t be intimidated by their quiet side, but make sure once you initiate a conversation with them, you are prepared to be invested. I have never much been interested in JUST sidewalk talk. Introverts are quiet most of the time because they feel people most likely aren’t going to listen anyway; show them that you’re different and you’re ready to truly be interested.
2. Make sure your body language is on par with what you are saying
Basically, be genuine. Introverts are good body language readers primarily because they rely on that (since they are so quiet) to get a feel for situations. If you are asking them questions but have your arms crossed, your body turned away from them, or you aren’t concentrating on what they are saying, it is extremely obvious. Why even bother if you aren’t going into it with 100% effort?
3. Give them time to be able to reflect on their answer and get back to you
Text, talk, email – throw a question at them but give them some time to think about it and open up to the idea of sharing with you. If it is a serious question, they can’t answer it with you 10 minutes before you plan to go to bed or leave. Give them some time to formulate their answer; they aren’t used to being put on the spot. If you want them to talk, you have to make them feel comfortable and sometimes that means being around them all day until they feel like you aren’t going to run away as soon as you hear the answer. Ultimately, comfort is the answer to a conversation with an introvert.
4. Share your own stories with them
Start by asking about them; if they aren’t ready to say that much, share a story that makes them laugh, makes them feel like you’re human, or reminds them of a story they have as well. People love to feel understood and like they can relate. If that doesn’t get them to open up or smile, you may want to reconsider if this person even wants to talk to you.
5. Ask them a question more than once
If they don’t answer a certain question right away, that doesn’t mean they never will. Be persistent. Sometimes they are just nervous. Show them it’s cool, you won’t judge them and you’re just as human as they are. It helps if you are open-minded and don’t jump down their throats about their views or experiences. Be conscious of how you may be taken and how they might feel.
6. Be patient
If you have no patience and are easily frustrated, this may not be for you. If you do an introvert to open up and talk, don’t immediately interrupt them or disagree with whatever they are saying or they will put up a wall again. They gave you their attention and listened without being combative, the least you can do is give them the same respect.