How do I write a good prompt to get the image I want?

Start with your subject, then layer in style, lighting, composition, and mood. For example: 'A young woman reading a book in a cozy café, warm golden hour lighting, soft bokeh background, photorealistic, Canon 85mm f/1.4' is far more effective than 'woman in café.' Include art style (photorealistic, oil painting, anime), camera details (lens, angle), lighting conditions, and specific colors or textures. The more precise your description, the closer the output matches your vision.