>>8932862
Be as descriptive as possible and if you could, drawing a little sketch if your intended vision, even with stick figures, is usually regarded to be a help to the artist. Provide reference photos on your idea, pose selection, underwear choice, along with images of the characters you're commissioning. If you aren't aware if they provide sketches during their process, ask them, that way you could suggest changes to be made if there's anything wrong about the sketch. If they leave it you hanging for a month without telling you they would, that's likely a good time to ask what's up. That's about all that comes to mind right now.

It's not a scary process, the artist is usually happy to be doing it for pay, ultimately.