The community-standard SDXL negative prompt. Weighted parentheses (e.g. :1.4) push the model harder against the lowest-quality artifacts while leaving room for style.
(worst quality, low quality, normal quality, low-res, low details, oversaturated, undersaturated, overexposed, underexposed, grayscale, bw, bad photo, bad photography, bad art:1.4), (watermark, signature, text font, username, error, logo, words, letters, digits, autograph, trademark, name:1.2), (blur, blurry, grainy), morbid, ugly, asymmetrical, mutated malformed, mutilated, poorly lit, bad shadow, draft, cropped, out of frame, cut off, censored, jpeg artifacts, out of focus, glitch, duplicate, (airbrushed, cartoon, anime, semi-realistic, CGI, render, blender, digital art, manga, amateur:1.3), (3D, 3D Game, 3D Game Scene, 3D Character:1.1), (bad hands, bad anatomy, bad body, bad face, bad teeth, bad arms, bad legs, deformities:1.3)
Source: https://www.aiarty.com/stable-diffusion-prompts/stable-diffusion-negative-prompt.htm