Start with silhouette
A fire creature needs to read before its surface effects do. Artists often begin with a wing span, a directional neck and a tail that carries momentum beyond the body.
A strong silhouette also supports accessibility: the subject remains legible at thumbnail scale and does not depend on color alone.
Light has a source
Convincing radiance changes nearby values. Warm cores, darker outer feathers and reflected light on stone tell the eye that the creature belongs in its environment.
Random glows flatten an image. Deliberate light establishes depth and directs attention.
Ornament follows anatomy
Gold lines, eye-like markings and flame shapes work best when they reinforce feather groups and joints. Ornament laid over the whole bird as an even pattern can make motion harder to read.
The final question is narrative: does the creature arrive, depart, guard or transform? Composition gives the answer before any caption can.