Please check out my eBay items for examples...
Add a Photo
It may seem obvious to some, but it's a great idea to show people exactly what they are bidding on, even show multiple angles for larger or intricate pieces. If you don't have a top notch camera you can improvise with your camera-phone or even invest in a cheap digital camera... See what deals you can find on eBay!
A good photo tip: Rather than get some crazy light set up for Uber pro looking photo's, if you have got a white bath, use that! it gives great lighting, and provides the big white background you need!
Describe Your Item
Again obvious but so many people out there don't even bother. If you're selling a fender guitar with a huge amp, don't just say electric guitar and amp, give specifics, the year, colour, condition, country of origin (in some cases) size, and any extras you might be throwing in regardless of how small it is. You can even give some history on the piece, the more people know, the more they will want the item!
Create a "My World" Page
You don't need any HTML skills, a degree in the inner workings of computers, or know the entire history of the common spoon. It's all laid out for you nice and simple, just fill in the form and include what you want. Its a great place to feature your TOS and tell people a bit about yourself. Its a small piece of customer care that a lot of people love to see, plus it saves putting the same old stuff in every auction, just put a link to your page!
The Right Price
Believe it or not, knocking 1p off of your starting price will save you in listing fees. Rather than sell an item for £10.00 set it at £9.99 and save about 10p on your listing.
Laying it Out
Another way to increase your sales margins is by using your own designs. A well Laid out advert will get you more interest than a pretty pattern around the outside. If you absolutely can't do without the border, use turbo lister, it adds them for free, that's another few pence saved! If you contact me I can help you to develop a professional looking template specifically for you.
Again it seems obvious, but it's better to be honest and get slightly less for the item, than to lie and get a negative mark on your feedback. Even when you're honest about the condition you'd be surprised how well it may do.
If you look at my Conditions of Sale you'll see that I say to wait for 5 days minimum for a cheque to clear. This is actually a lie, I post most items that sell for less than £10 the same day I receive the cheque. The reason I say wait for clearance is so that the guys with bad feedback don't moan when I wait for their cheques to clear. it costs more than £10 in Bank charges for a bounced cheque so no fool is going to willingly bounce a £9 cheque when it costs around £15 when it goes wrong. This gets you really good feedback from surprised buyers who have received the item quicker than they imagined they would. Again a happy buyer will come back!
Don't Be Scared of Newbies
For some reason a lot of sellers have newbie phobia (as I'm sure some of you noticed when you first joined). Don't worry about the newbie's, 90% of the time they will try harder to make things go smoothly because they want their first star, and don't want anything to go wrong with their first purchase! I have only ever had 1 non-payers, and he had 100 + feedback. He is now however blocked from bidding on any of my listings. Newbies pay quickly and communicate well. Take advantage of that!
Never Underestimate the Power of Television
It may sound crazy, but the last thing you want to be doing is selling an Aston Villa shirt, that finishes half way through an Aston Villa match that is shown live on TV. The last hour of your auction is the frenzy hour where bids can get into silly season. Take note of what's on TV, and guess how popular it is. For instance my target audience if I am selling an Ed Hardy dress will be females aged 16 - 35. These people like watching soaps and maybe How to Look Good Naked type shows. They may go to school/college/work and may not have the facilities to surf eBay during the day. Therefore I try to cater may sales time around that. Most of my auctions will either end on a weekend, or at about 6pm just before the evening soaps kick off when most people are at home and often surfing out of boredom.
Don't Use Reserves
A lot of people hate reserve prices, and will give up trying to guess how much you want for it after a while. If you want at least £10 for something, use it as your starting price. It may cost a bit more to list, but it's better to get the price you want, than paying for a listing that won't sell.