Before you sell anything, buy yourself a little present. "That way, you get to know how the system works," explains Marsha Collier, author of Starting an eBay Business for Dummies and a frequent instructor at eBay University. Bidding on an item not only puts you in the shoes of your future customers, but it will start boosting your feedback rating on the site. You don't have to spend a lot of money. There are some very low-cost items to be found on eBay--postcards, CDs by bands no one has ever heard of; even beads.
Spend time surfing eBay, looking at the auctions of items you might sell. Which ones are getting the bids? What key words do they use? Do they have gallery photos that show up when bidders browse categories or search listings? Collier also suggests you search completed items (you'll find this option in advanced search) to see what items actually sold and for what price. This will help you determine if the products you're interested in have a market and a big enough profit margin on eBay.
Spend time in the Help section, too. This is where you'll start to understand the different types of auctions, the many features you can use when listing items, the rules and regulations of the site, the levels of feedback and what you can do when something goes wrong.
Finally, do some research on your own. Selling on eBay may be a cinch to set up, but good business sense is what guides you in the long term. Take advantage of business books, sites like ours, eBay guides like Collier's, and eBay's own resources, such as the aforementioned Help section and eBay University. eBay is genius at customer service and wanting to help their sellers succeed. Yes, it's self-serving--if they help you succeed in business, they'll get more money in their own coffers. But hey, you need all the help you can get, so why not go to the source?