Many first time sellers have 1 thing in common - they fail. Many of them fail time and time again, never understanding what is going wrong. They do hours of research looking for the perfect item to sell, get the auction set up, and wait for the bidding to begin. Hours go by and no bids are placed. Days go by, and there are still no bids - or there are very low bids. Finally the auction ends, and it turns out to be a total failure. Considering the huge number of sellers who run eBay auctions, there are specific things you must do, and specific things you must not do if you are to be successful.
There are many reasons why auctions fail. The most common reason is that the item is not in high demand. This problem can be avoided by doing the necessary research to determine which items sell well, and which items should be avoided. This research takes a great deal of time - but in the end, you will find that it is time well spent.
Another reason for eBay failure is pricing. No matter what your reserve price is, your opening bid price should never be more than $50 or so. This is how you will attract potential bidders to your auction. If you set that opening bid too high, most people won't even click the link to read the description for your item. Another pricing problem is lack of research. Before you set your reserve price, you must determine what the item is really worth, and the price similar items have sold for in past eBay auctions.
Poorly written descriptions are another cause of failed auctions. Poor grammar and misspelled words drive people away. Failing to post a picture of the item will also keep people from visiting your auction page. Make sure that your description is well written. This is essentially your 'sales copy.'
Shipping prices scare people away from auctions if they are too high. Find the lowest shipping prices that you can find, and consider paying for the shipping yourself if it won't cut into your profits too much. Do not charge handling fees.
Offer great 'customer service' for all of your auctions, and ask your buyers to give you feedback. If the items that you sell are everything that you said they would be, and you offer great customer service, you can expect remarkable feedback - and this feedback will help a great deal in your future auctions.