I think it's different for everyone. One way is to try and move yourself out of your comfort zone. One way to do this sounds kind of silly, but it's to just strike up conversations with people. There are a few topics that are almost universal to everyone to talk about, depending on the situation your in. For example, if your in school and you want to talk to the people in your class, talking about assignments is a good easy conversation starter since you know you all share the same assignments. Trying stuff like this really helped me, but it still takes time

As alwYs exposure, but in very very small amounts and build over time in larger time allowences and longer exposure