Other sites are more selective, and more costly, but better focused. Onsale works with specific industries, and has very few non-auction items. You will also pay more and have fewer potential customers. You also need to find a way to draw attention to your item. Include pictures as much as possible.
Pictures can reduce customer wariness bcause they can see a product before buying.
You will also want to include methods for contacting you. The customer may have questions, and may not be willing to bid before they are answered. Finally, be clear but clever in your description. The more people that decide to look at the item, the more bids you can generate. Increased bids will improve revenues.