The trick is to be specific, but not robotic. Imagine you're giving directions to a highly skilled but literal artist. Instead of saying 'a cat', describe it in more detail: 'a fluffy grey cat napping in a sunbeam, vintage oil painting style'. Details such as lighting, mood and style are very helpful. Also, don’t forget negative prompts. For more examples and tips, check out this great guide on how to write prompts to generate images:
https://wishapp.ai/en/blog/how-to-write-promt-for-flux-neural-network-secrets-and-examples .