The five building blocks
Role, task, context, format and constraints. Most weak prompts are missing two of the five.
Role: You are a [role].
Task: [what to do].
Context: [background].
Format: [bullets / table / 3 paragraphs].
Constraints: [length, tone, things to avoid].
Show an example
One good example beats a paragraph of description. Paste a sample of the output you want and ask the model to match it.
Iterate in small steps
Change one thing at a time and keep the winners. A tiny library of proven prompts is worth more than a thousand untested ones.

Comments & Discussion (2)
Great explanation of the differences. The comparison really helped me decide.
Bookmarked. I have been looking for a clear walkthrough like this.