Learn to use conversational threading. What's that, you say? Imagine someone tells you a story:
"The cat run up the tree and we had to call the fire department to get him down".
Here you have 4 topics:
-Running (up a tree)
You can use any of those 4 topics to go into another direction. So as people talk about [stuff], think about the topics related to it, and go through your mental database of stories and facts, and see if you can make a statement about anything related to that. Remember, statements, not question. You need to talk too, not just ask questions over and over. This can feel artificial but it'll get automatic with time. It's just a new habit you need to train for a while.