Personalmente comienzo (obviamente después de la presentación y a que te dedicas y esas cosas) con temas que son mundialmente conocidos, como películas, me gusta mucho conocer como se cantan las canciones de Disney en su idioma por ejemplo, el libro favorito,etc. después conocer un poco más de su cultura, como la comida, que comimos hoy, etc. y así van cobrando complejidad las conversaciones. 

Si gustas algún día podemos practicar, también entre mexicanos se aprende inglés. 

When I have video calls, I prefer to have things to look at and to work with.  I prefer to have articles, pictures, or videos to discuss instead of having just conversations with no focus. 

For Spanish/English exchange, for example, one of the activities that works well is using these sites:  https://www.gocomics.com/comics/popular

https://www.gocomics.com/comics/espanol

Many of the comics on the pages above, like Garfield or Calvin and Hobbs, have the same comics in English and in Spanish.  You can look at them together, read them for pronunciation, but especially try to translate them yourselves together and the peek at the professional translation. 

I also like to do things like use bing images, put in a term like ¨street art¨ and then talk about what you see in the pictures. (¨street art¨is one of the terms that gives you lots of different things to look at and talk about.)

I also like to use videos of the parts of the country each of us are from, without the sound.  I find it much more interesting than conversations and more workable if one of the partner´s conversational skills are not yet good.  You can always find things in the videos and pictures to add more vocabulary.