I've had many people ask me for photography tips, so here's all of them in one place for easy reference.
A common misconception about taking good pictures is that you need specialized equipment. This is completely untrue. What you do need is a camera with a good macro function. I have an older Nikon 990. I've had it for about 7-8 years, and I bought it used from a photographer friend of mine who was upgrading to a camera that would allow him to use digital and film.
That's the expensive part. The rest you can do with simple common materials you have around the house. My current "studio" consists of the box in which my last order of padded mailers was shipped, covered by a fabric remnant, in front of the french doors in the dining room, which face due East. I put the box right next to the doors. On sunny mornings, I leave the white blinds drawn. On overcast days, or in the afternoon, I can raise them, or open the door and enjoy the weather while I work. I've also covered up one of the kitchen chairs with satin and pulled it over to the French doors as well.
And here's some pictures taken with each setup:
I've experimented with a lightbox that I purchased, and have found that I actually get better pictures with my homemade setup. The disadvantage is I am limited to daylight hours to do my picture taking.
Some people use props to give their pictures a little more life or depth. Make sure if you choose to do this that the items don't overwhelm your product. Here's a couple of examples from the stores of my fellow Jewelry on Etsy teammates:
Evening Blue, by mcrdesigns:
The Rolling Stone Ring, by capitalcitycrafts:
And using a mannequin or a person to show your potential customer how the necklace lies when worn can also be important. See this lovely piece by TheBrassHussy:
Another essential - a photo editing program. I use photoshop, but there are many other possibilities. Each of these images has had the lighting level adjusted slightly, and all are cropped to best frame the image. You can also change the angles to provide more interest in your shots. A full page of items photographed in exactly the same manner won't draw people in as much as a selection of varied images.
There are several free photoediting programs available. I've used Picasa in the past, and if you do a google search, you'll find multiple other programs and can decide which works the best for you.