Jobs at small Minneapolis companies nobody posts about - 13 months and counting

A friend who works at a local manufacturer says there are openings not advertised online. I do not usually post, so bear with me. One is a print shop, one is an accounting firm and one is a clinic. Should I visit in person?

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

Keep a list of who you contacted and when. It makes follow-ups easy.