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

A friend who works at a local manufacturer says there are openings not advertised online. I have been trying to stay organised about it. They prefer people who can start within a couple of weeks. What do you write in a cold email?

Thanks for writing this out. I went through something close to it 11 months ago, and it got easier once I kept a simple log of every call and form.