Even if you and the artist have previously agreed on content and scenes and set-pieces, clear and specific notation of the mechanics of the comic is down to you. You are telling the artist what to do. The trick is to get the artist to like it
You are, in many ways, writing a love letter intended to woo the artist into giving their best possible work to the job. A bored or unengaged artist will show up on the page like a fibrous stool in the toilet bowl, and that’s not their fault — it’s yours.