Word-of-mouth leads in Kansas City

Two small Kansas City employers told me they are hiring but have not posted yet. This is my first time dealing with any of this. One is a print shop, one is an accounting firm and one is a clinic. What do you write in a cold email?

A short email with two sentences about what you can do and your résumé attached worked for me. I followed up after a week.

Visiting in person worked for a trades job. For office jobs, email was better.