Check out img2prompt to turn any image you like into a prompt for inspiration.
The further to the beginning of the prompt a word is placed, the greater its effect. Use multiple exclamation marks !! to stress a word and brackets () to reduce its strength. The latter does not work with all implementations. In the Automatic1111 webui () will stress a word instead.
3D renders & realism
Will improve the image: unreal engine, octane render, bokeh, vray, houdini render, quixel megascans, arnold render, 8k uhd, raytracing, cgi, lumen reflections, cgsociety, ultra realistic, 100mm, film photography, dslr, cinema4d, studio quality, film grain
Will achieve specific style: analog photo, polaroid, macro photography, overglaze, volumetric fog, depth of field (or dof), silhouette, motion lines, motion blur, fisheye, ultra-wide angle
Try experimenting with the names of professional cameras (e. g. Fujifilm XT3 or Canon Eos 5D) and lens specifications (e. g. 80mm Sigma f/1.4 or any ZEISS lens).
Will improve the image: digital art, digital painting, trending on artstation, golden ratio, evocative, award winning, shiny, smooth, surreal, divine, celestial, elegant, oil painting (helps improve multiple styles), soft, fascinating, fine art, official art, keyvisual
Will achieve specific style: color page, halftone, character design, concept art, symmetry, pixiv fanbox (for anime/manga), trending on dribbble (for vector graphics), precise lineart, tarot card
Note that Stable Diffusion's output quality is more dependant on artists' names than those of DALL-E and Midjourney. Without atleast one artist name the output might look like a beginner's work. Finetuned models like Waifu Diffusion and NovelAI can work without artist names.
For Waifu Diffusion and NovelAI, use Danbooru tags for the best results because they are both trained on a Danbooru scrape.