Jobs at small Dallas companies nobody posts about - any advice?

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

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

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