Someone told me the other day that she thought I did an excellent job at photographing my items for ebay, and she asked for tips. I had to laugh because I have really struggled, and still do sometimes, to get just the right photo. I did give her a few simple tips, though, and thought I would share them here as well.
Tip one is to use a lot of light. We recently bought one of the large silver, dome-shaped, clamp-on lights and got a Reveal by GE lightbulb, which produces a very nice, clean, bright light. I back that up (unless I get lazy) with a second one (one we had, which is smaller) and use a white sheet (most of the time - unless it's a light-colored item and then I use red or dark blue) as a backdrop and surface. Position the lights in such a way to avoid shadows as much as possible (or let the shadows help to show off the shape of the item).
When you compose the photo, try to fill the frame with the item you're photographing and, most certainly, avoid clutter in the background. Look beyond the item to see what will show, in two dimension, in the background. (Did you ever take a picture then get it back and see a tree growing out of the person's head? The tree was there all the time, in the distance in 3D! You just have to learn to look beyond the subject and see the result which, remember, will be flat.)
What has helped me the most is to use Picasa, the free photo-editing software that you can find by doing an internet search. It is very easy to use. Even with good light my pictures are still somewhat yellow, so I use the Auto Color feature to level that out, the Auto Contrast if I feel it needs it, then add fill light if necessary. I crop the picture to delete as much of the background as possible and I try to make a vertical aspect, as I mentioned in another one of my guides, if I'm going to use the picture as a gallery photo because it takes up more space on the search results page.
There are many other solutions for photo problems, including using a purchased or homemade light tent or light box and a tripod to avoid blurriness from camera shake, and I may elaborate on those later. In the meantime, I hope these few hints are useful for you.
Have a great ebay day!