you may want to try the sister site for some tips
your canon should be fine...some tips
try to shoot in natural light without the flash especially for close ups
if they come out too dark increase the iso film speed setting.
find out what your cameras close focusing distance is...if your are closer than the lens can focus your pics will be blurry.
stay with neutral backgrounds...not white or black...these can fool your meter to under or overexpose the pics. this should get you started...or confused.
Use a single light such as daylight (or tungsten and proper camera settings), and use white cardboard to fill shadows and provide the reflections for your equipment.
Nature provides only one light and often that is all that is required in product lighting. I use this method, employing aluminum foil covered flats and white boards too.
If possible, download a trial version of Photoshop (one of the simple versions). This will allow you to lighten, darken and do color corrections as well as sizing the image to Audiogon's requirements.
Samples of my photography may at the link below. I do many products for audio advertisers.
Nice clean work Albert! I'm a pro too. Been at it for 21 years now. There've been some really excellent suggestions here already, so I'll just recap the ones I would stress:
1. Light is probably the most important key to answering your question. A single diffuse light source, as Albert reccommends, is great and makes most products look good. Large white cards for fill are also very helpful. I like the north sky for light..that is an open sky without direct sunlight. A direct point-source of light, like the tiny flash on your camera, or the direct sun, is more likely going to make your images look harsh and unappealing. If you can't drag your gear to the window or outside to shoot it I'd say try your best to replicate a diffuse light source. This is all but impossible if you insist on using the little flash on your camera as the main light (the suggestion to diffuse it is a good one, but ultimately still tends to look rather harsh. Go on to point #2 for more on this...
2. Always use a tripod. No other acessory is going to make a more consistent improvement in your image sharpness, clarity and detail. If a tripod is not available then do your best to brace your body against some solid object when taking the picture. Once the camera is on a tripod you don't have to worry much about longer exposure times that come with using artificial lighting. Here is where you can create your own artificial diffuse light source (as long as the camera is on a tripod). Get as bright a light source as you can (a flood light will do). You can either bounce this source off of a large white card (maybe 3X4 feet, the bigger the better) or surface (a white wall if it is convenient), or perhaps get a white bed sheet and point the light through the sheet at the components you are shooting. Keep the light back from the sheet or white surface so that the flood of light covers much of the surface. You want to do this with a neutral white sheet/surface. Using a warm sheet would likely result in warm photos (not necessarily a bad thing). In either case those white cards to fill in will still come in handy here as they would using daylight. If you are using artificial light make sure to change your camera's setting (or film if you use it) to Tungsten (indoor light). Try to position the light off-axis of the lens (to one side or the other), and perhaps a bit higher than the camera.
3. On close-ups make sure you are not getting closer than the range of your camera, and that the camera is set for close settings (many digitals do have a setting for going in closer).
4. Photoshop is an excellent program for image manipulation and is certainly the industry standard. It is pretty complex, but well worth learning the basics. Do make sure to size your digital files for effective use on the Internet. The webdesign standard used to be to make all images around 480 pixels high which is the height of a pretty small screen (or what a browser would provide on such a small screen). Knowing most folks do have slightly larger screens I tend to make mine at least 600 pixels high. Computer screens resolve 72dpi. If you are only posting your pic to the internet it doesn't make much sense to make them any finer than that. The .jpg format works very well for posting images to the Internet.
My photography is mostly illustrative for advertising, graphic design and editorial purposes. Quite different from Albert's, but I do architecture and motorcycles as well (on the image pond site search under "Category - Architecture or Sports) Here are a few links: