EBay selling is not rocket science. Anyone can do it. But it helps if you do a little research and thinking before you plunge in.
Whatever you are going to sell, take a look first and see if others have advertized the same items. Use their listings and prices as a guide to what you are planning to sell. This will prevent you from claiming that your item is 'rare' or 'unusual' or 'hard-to-find'. See how they describe the item - would it make you want to buy it ? Put a watch on items, so that you can monitor their progress and final selling price. That way you can see just how the market is.
When you come to describe your item, do so accurately, without too much hype, false claims or over the top excitement. If someone has clicked on your listing, then they may well know more about it than you do and they will not be impressed if you are making unjustified or wild statements. If you don't know, don't invent things. There is no shame in admitting that you may not know too much about an item and it is better to plead ignorance, describe it to the best of your ability or knowledge, than make it up.
The listing title is all important. Use all the spaces and put in as many buzz-words as you can. It does not have to be gramatical or make total sense. Do NOT waste space putting WOW or COOL or words like that. No one is going to search using them, so put as many words as you can think of that someone might be using to search for an item. Check your spelling before you complete the listing. Potential buyers will search by the correct spelling, not by your mistakes.
Make sure you have listed your item in the right category. It is amazing how many people do not.
Pictures will always help ... remember the maxim of "One picture is worth a thousand words...". Just make sure it is a GOOD picture. Out of focus or too distant images will not help you. Make sure is the right way up ! As they are free, put in as many as will help someone decide that they want the item. It can be time consuming to take them and upload them, but if it will make the sale, then it is always worthwhile
When it comes to pricing, again be guided by others. Dont start off with wildly high prices, as the item will probably just sit there. It is the psychology of selling. If a buyer sees an incredibly high or artificially inflated price, it doesn't matter how much he or she may actually want the item, they just will NOT bid. Let the bidders do the work there. If it is something that you really don't want to sell under a certain price, then put in a reserve, but be aware that this often puts buyers off, so use it only when really necessary.
Keep the shipping prices sensible. If you have a lightweight item that needs little in the way of extra packing or protection, then keep the mailing costs low. Nothing puts potential bidders off faster than when you charge a vast amount for an easily shipped item. Always give the shipping prices or at least a guideline in the listing. It is silly not to and you can either have potential bidders NOT bid because they dont want to waste time contacting you to ask and you from your side, do not need the be tied up answering emails that would not be necessary had you put the shipping price in the listing to begin with. If you are a private individual, do you really need to charge for "handling"? Would you have been doing something else in the time that it takes to pack something and the Post Office is usually in the center of town and you were going there anyway. Give an option to customers for shipping methods. Many do not mind waiting or do not need the item immediately and are happy to take a cheaper, if slower, delivery.
Be honest. If something goes wrong, whether within or out of your control, admit it and act sensibly.
I hope this has helped.