Word-of-mouth leads in Boston - any advice?

A friend who works at a local manufacturer says there are openings not advertised online. I would rather hear the honest version than the polite one. One is a print shop, one is an accounting firm and one is a clinic. Does anyone have similar leads?

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

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