You have to admit, Mary O'Donnell doesn't look worried. Photo by Chip Scheuer.
— Keep everything clean when you’re composing the jars, but don’t worry about sanitizing. The tomatoes aren’t sanitized, after all. Everything is sanitized in the hot water bath.
— The better your tomatoes taste fresh, the better they’ll taste canned. This extends to bruised tomatoes.
— No need to remove the skins—they’ll slough off post-canning.
— Make sure your jars are summer room temperature (fairly warm) before putting them in the hot water bath or the contents won’t heat properly.
— If a seal breaks and the jar contents become unsafe to eat, you’ll know. Would you eat oozing or carbonated salsa? Didn’t think so.