A good first prompt has three things in it, in this order: what it is, who it's for, and what it should feel like.
YOU TYPE
Build a one-page site for my pottery class sign-ups. It's for parents booking a Saturday morning class. Keep it warm and simple, not corporate.
Notice what's missing: no mention of colors, no mention of "responsive design," no technical words at all. That's on purpose. The AI can make reasonable technical decisions on its own. It cannot guess who the page is for or what feeling you're going for, unless you say so.
THE MOST COMMON BEGINNER MISTAKE: writing a prompt that's all technical spec and no context: "make a page with a header, three columns, and a footer." That gets you a page. It rarely gets you the right page, because you never said what it was for.
TRY IT: rewrite one of your old, vague prompt attempts using the what / who / feel structure. Notice the difference in what comes back.