01 ·Context
A skill is one job, written down once, so the AI runs it the same way every time.
The shape of your weekly client update. The way you size up a new lead. The five things you check every Monday before coffee. Write it down once and you stop re-explaining it.
The one rule that matters: do not start by writing the skill. Most people hear the word, get excited, and try to build one cold. Wrong order. You write a careful file for a job you do not understand yet, and it is wrong in ways you cannot see.
Start with the prompt instead. Do the job the slow way. Type out what you want, in plain words, every time you do it. Next time, fix the part that came out wrong. The week after, tighten it again. You start saving the good version and pasting it back in, because retyping it is annoying. That annoyance is the signal. When you would happily paste the same prompt every time, that is the moment to write the skill. It is just that refined prompt, given a name and a home in a file.