It's important to have a complete inventory of available conversational subjects (strokes) that have worked in past volleys. As you build an inventory, you will be able to rely on these proven subjects in confidence. I suggest you avoid the common (and boring) stuff - weather, weekend plans, where you live, schooling etc. Instead think of some subjects that you would find interesting.
Tell me about any home projects you planning or doing now.
What are your family traditions at .... Christmas, Easter, Fourth of July etc.
What are your favorite restaurants around town... Why
Books, Movies, TV Series, Songs are good ways to learn about someone.
Asking about preferences and understanding their thinking can be enlightening.
What's your favorite technology gadget and how did you discover it.
You will find some of your strokes will come back quickly and require fast exchanges back and forth. Other subjects will be "deep" and give you plenty of time to plan a response. Picking the right stroke for the other player is a skill you will develop based on your inventory of subjects and the talent of the other player.
Instead of just creating a sigh of relief when the conversation volley is done, look back on the game and analyze what worked and what didn't work. This conversational analysis will add to your skill in future play.