I know this may be a bit dismissive, but I think the need to ask that is the problem. AI can definitely build a design for you. But is no substitute for design skill.
The best way to figure out how to prompt an LLM is to develop design skills so you know what to tell it.
I’ve been in the industry a long time. Even before LLMs, I think web design would get stuck in cycles. So I just want it to spit out something that looks novel and interesting, which pushes me to coach it even better.
This might sound like a joke but it’s a surprisingly good take. RSCSS provides a great set of principles to structure and isolate against unintended change. Open Props can be added for design tokens and Open UI has some great examples of components.
The best way to figure out how to prompt an LLM is to develop design skills so you know what to tell it.