Flux Schnell is a powerhouse, but garbage in equals garbage out.
Describing Lighting
Don't just say "a dark room." Say "Cinematic low-key lighting, volumetric fog, neon orange accents, 8k resolution."
Camera Angles
Specify the lens. "35mm street photography" looks very different from "Wide angle 14mm architectural shot."
Negative Prompting
Always exclude things like "deformed hands," "blurry faces," and "low resolution" to maintain the highest quality.