Small employers hiring around Chicago - first time posting

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

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

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.