I have a friend who is willing to help me speaking a relatively rare language here in the U.S. (Afaan Oromo) once a week over the phone. When I was calling him regularly several months ago, I would often run out of things to say. What are the best types of exercises (or vocab vs. grammar) for me to practice daily on the days when I'm preparing to speak with him.
(Other info: I have basic greeting and some vocab down; I don't have a lot of time to study so I would average 15 minutes of studying)