Writing an art brief
An art brief is the document you hand an artist describing what to create. A good brief is the difference between getting your vision on the first pass and burning through paid revisions while you both get frustrated. The core skill is describing outcomes, not brushstrokes: what the image needs to communicate, who is in it, what mood it carries, and where it will live in the game.
A solid per-piece brief covers a few things. The subject: who or what is depicted, with any details that matter to the game ("the alchemist is elderly, wears green, and must be recognizable at card size"). The mood and moment: is this triumphant, ominous, comic? The composition constraints: where text boxes and frames will overlap the art, and which areas must stay clear. The context: what the piece sits next to, so the set feels cohesive. Reference images are worth paragraphs, pull examples of style, palette, and framing you like, and a couple you specifically do not.
For the project as a whole, include a style guide even if it is one page: overall tone, color palette, the game's setting, and a canonical reference for any character or faction that appears more than once. Consistency errors, the hero's cloak changing color between cards, are the most common and most avoidable revision cost in a multi-piece commission.
Agree on the revision process inside the brief: how many rounds are included, and at what stage feedback happens. The cheapest place to change an image is the sketch. Give thorough feedback on sketches and thumbnails, and avoid discovering at final render that the composition was wrong all along.
Video tutorials
How to Write a Plot for your Story [Writer's Dice - Kickstarter Video]
Time to make my fortune on Kickstarter? | Your Game Design Opinions and Insights