Mindset is important, so no matter how few items you're selling, always look at what you're doing as a business. Appearing professional will always make a positive impression on your customers. Take a look at the sellers who have the best feedback scores. Locate sellers with the highest number of products for sale. Now look at their listings and the things people have said about them. You'll probably see that 'professional' word mentioned a lot.
Prior to listing your product for sale, be very sure you perform some basic research. Do some research to find products already listed that are exactly the same as your product, or even somewhat the same. You want to get an idea about prices, so if you find similar products record the 'Buy Now' and starting bid prices and save for later. Pay particular attention to those listings with high numbers of bids and views. Ok, check out the relevant listings, and then figure out what will work with your product/listing. Then it's just adapt what you can to improve upon, or create, your listing. This is basic market research strategy. What you're doing is building a better mousetrap for your own business.
Whenever you make sales, be sure to ship the item out quickly. Ship it out as soon after the sale as you possibly can. If you have many listings in place, you may fall a little behind with your trips to the post office or UPS store. It is important, however, that you send out your products within 24 hours of making the sale. If you want to build up your feedback score, shipping items quickly is one of the best ways to do this.
What's good about Ebay is that anyone can open an account and start selling right away. In fact it might just be the very easiest way to make money online there is. Many people begin selling items from their garage or attic and then go on to create a highly profitable online business. Even if you are interested in other types of internet marketing, Ebay can be a good way to start out and get familiar with selling online. This is actually how some of the most successful internet marketers began their careers. Don't underestimate the income potential of selling on Ebay; many people make full time incomes by doing this.