The very first don't: don't use the flash! Camera flashes wash out colors, creates sharp reflections on your metal, and quite frankly, appears very amatuer-ish. DO purchase (or make) a light tent or table top photo studio. I got mine (pictured below) at Amazon.com for a very reasonable price that also included two lights, 1GB memory card, a tripod, and all sorts of care supplies for my camera. And your camera must have a macro option...a lens capability that allows for up-close photographing. No fancy camera is needed. Many companies sell cameras around $150 with adequate macro. I personally have a Canon A530. The lag time between shots is rather long, but my subject isn't moving, so I can live with this!
Do find a spot to set up your photo studio, permanently. Locating your studio next to a bright window (not direct sun if possible) is key. Natural light is the best for jewelry photographs. To save space, I set mine up on the bench where my rolling is mounted. Do use a tripod if you are unsteady. Do invest in nice tabletop photo lights if you will be photographing in dark conditions.
DO be consistent with your backgrounds and props. When viewing a shop, customers prefer a harmonious arrangement of colors and textures. Backgrounds can distract or enhance. Love the bright tropical colors of the Bahamas? Awesome, just don't mix in photographs with backgrounds of moody, earthy ochres and mosses. Along with backgrounds, props can create a "story" within your work. What is the story you would like to tell? Nature lovers love jewelry, too? Grandmother's attic is full of surprises? Quiet day by the lake with a good book? You get the idea!!
Have your props ready to go when you are ready to shoot. Above is my current line-up that I am slowly introducing into my photos. By keeping your props gathered together next to your photo studio, you will save time and will be able to list your lovelies sooner than later!
Do crop and play with the brightness and saturation. Sometimes, even in the best conditions, the photo's color and brightness are not as you saw with your own eyes. When cropping your photos, play with these adjustments for optimum results. Also, experience with subject positioning. Sometimes showing a portion of the item will entice the potential customer to click to see more. Follow these simple rules and your Paypal account will thank you!