I started writing in theatre so dialogue comes naturally to me (I'm also a talker from a family of talkers lol).
The part that's hard with audio drama, especially if you don't use narration, is creating what's going on around you without saying "on the nose" things like "I see that's a $25.00 ticketyou have for the play" You have to change the dialog to something like "How much do I owe you?" answer "25 bucks" answer "okay, gimme the ticket" and then, of course, have the appropriate sound effects in the back. That's WAAAAAY over simplified but it's doable. One of my plays for my old company was done on a dare and it was a story without narration but only one actor.