There are three things that directly effect your profits, two of them you totally control the third EBay takes care of. These things are most importantly what will sell you product, they are: the pictures, the description and the advertising.
Okay, lets start with the description of your product and it's title. First, the title, make this both informative telling the customer about what the product is but also make it interesting, you are one of many listings that are trying to sell the same thing. The description is where you have the most creative license, here you have to fully describe your product, it's features and anything that the customer may want to know. You also have to put the product in its best light, think about it's many befits of buying it and try to get that message across. If you can think of any reasons not to buy it include these as well. Make sure you dismiss the argument by showing a counter argument! It's a very powerful technique.
Now the picture, we have all seen those photos where it is just taken off the Internet and the product is in perfect condition, so we know how annoying it is to see them. Don't use them, instead you have to take suitable pictures of your item. If you continually sell on EBay your own camera is a must. You will want a to take a few photos of the item. You will need a general shot showing the entire object also some close-ups, these will give the feeling to the customer that you are not trying to hide anything. When you take it you want to have a contrasting colour as the background, for example lay some white sheets of paper down against a black object. You should take the photo in natural light, avoid glare and don't use the camera's flash feature as the photo will probably end up overexposed otherwise.
Finally advertising, you can chooses to pay for advertising yourself if you need to have a lot of bids, but just having your items on EBay will mean it will get a lot of exposure.
A final tip, if you are trying to sell an expensive item I would recommend that you get the item professionally inspected and sell it at an auction house and not online. If you do sell on EBay have professional photos of your item taken and get the description written for you.
