Theaterfag who's read a screenwriting book here.
A very important thing to be aware of is Diminishing Returns. Doing funny voices for kobolds and goblins is a staple that everyone should do at least once. You start out by talking in-character, and if it gets old or doesn't work, you phase it out in favor of describing what your character says.
Performance is such a multifaceted topic in general. Proper, capital "D" Dialogue (that serves to convey information to the audience) is purposefully written, and goes through multiple drafts, so it's basically impossible to improvise. If an NPC has to deliver exposition, you are better off narrating it, including describing tone, pauses, and body language. Not because you're a bunch of autists who can't interpret body language, or because acting is "too hard", but because you get one take without any prior feedback, and communicating the information is more important than getting to feel like an actor in front of 2-5 people.
On the flipside, when it comes to improvised interactions that are actually fun to watch, two amateurs with good chemistry beats two professionals with no chemistry every time. But this results in something that you had to be there to appreciate.
I find a good rule of thumb is to talk in-character if you think of a good line, or if it's just more straightforward, and describe anything more complicated than that.
>>96250894
I got into OSR recently, and I run sort of OSR-adjacent games. The procedural play introduces logistical problems for the players to overcome, and it creates a petri dish for organically growing war / expedition stories. A lot of the play reports are very dry, but a good storyteller knows how to cherry-pick the interesting bits and assemble them into a story worth retelling.
