Jobs at small Denver companies nobody posts about - what worked for you?

Two small Denver 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?

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.