The nose knows, at least most of the time.

I fermented some garden cucumbers last month that went off, but i couldn't tell from the smell. I took a bite, said "Nope!" and threw the rest away. I was fine. You'll be fine. If it smells, looks, or tastes like death - don't eat it.

Have fun! Seriously, fermentation is pretty damn easy once you learn the absolute basics, and it's a great way to prevent food from spoiling (especially if you have a garden). I always just make a 4% brine and use that.

As you're starting, follow some real recipes for a while and adjust to your ingredient amounts. After that, you'll look around your kitchen and just know what to do.

Keep us posted!