Trying to figure out the photography thing

Sometimes I take pictures and they turn out like this. Sometimes...well, not so good. I can't seem to figure out the secret to taking consistently good pictures.

My main problem is that most of my items contain metal (base metal mostly, but sometimes sterling silver) crucifixes, centerpieces, and medals. If I have the lighting so that the color of the beads are more true-to-life, I get a mad glare on the medal components. If I have the lighting so that there isn't a glare and the detail of the metal components is clear, the picture is too darn dark. ARGH!

I read an article that suggested setting the camera's f stop to 8 and the ISO to 80-100. I've figured out how to set the ISO, but not so much the f stop (although the camera loves to tell me what it's currently set to).

The worst glare, however, is on my pinback buttons. The buttons look so much better IRL than they do in the pictures.

Photography...the bane of an Etsy seller's existence ;)