Describe the character
The character, be it human, animal, robot or a creature, is the focus of the artwork, unless you're ordering landscape concept art or maps. When describing it, focus on the basic description of their appearance, but also mention a sentence or two about their personality, as it's important to match the mood and character's expression.
If you have a picture of character or their concept art piece, you can use that instead.
Physical traits (height, weight, body type, body shape, phenotype or ethnicity).
Palette (skin, eye and hair colors).
Fashion (clothing style, clothing color palette).
Personality (short and concise description of character traits).
Whole D&D character sheet - I don't have the time to sift through the information myself.
The backstory on every fucking tree branch - Keep your description character relevant, please.