As someone who both buys and sells a lot on eBay privately, I often see listings which don't seem to grab much attention, and at the same time see quite obvious reasons why. As a buyer, this is usually great as it means we get the items cheaper, but at the same time I feel quite sorry for the seller. This guide is for the sellers out there to maximize the profit from their listings.
My most recent experience which led me to this was when I recently bought a rack gear case. The photo showed the case open with the lids removed, and the listing never mentioned lids. These cases usually fetch £40-50, but I won it for a fiver. The seller seemed a little annoyed at this, understandably, but when I collected it the lids were included (which would be the main thing to put off other bidders) - if he had mentioned they were included he would have probably got a lot of money for it.
Another item recently was a Boss guitar pedal. There are a lot of people out there (Like me) who collect these, and there are quite a few variations on them. I've just watched one sell which merely looked like it had a few scratches and cosmetic pieces missing, it sold for £15. I had been talking to the seller though, and he never mentioned in the listing that it was one of the sacred "Black Label" pedals, in which case it should have sold for more around the £50 mark, maybe more, as they are quite rare now.
There is two examples of how a bad listing will seriously affect your final selling price. I always think, if you find something lying around and don't know what it is, research it a bit. contact the company, google it, whatever. just so you find more information about it and get a better price. its the little things like the colour of the label or a screw, or a certain sticker in a different place etc which turns the item from being just a normal standard one you can get new, to being a rare vintage collectible, and knowing those details could be hundreds of pounds in difference.
My next tip would be to describe everything. I always think of it as "A pound per line" - if you type 5 lines about something, you aren't describing it much and won't get that much for it as people wont know the info they need. if you type 50 lines, you are more likely to get more money for it as people know the details. obviously if you write 500 lines about something thats worth £9.99, you wont get 500 for it - this is more just a guideline, write more about things with a higher value to make sure you achieve that value.
Tip number 3: Photos. A lot of people only put up one photo of the item to get an overview, saying extra photos are too expensive. When you think about it, 12p is really not that much. you probably could find that under your bed side table, and it will earn you more than 12p back. I think if an item is expected to get any more than around £30, you should be looking at getting the smaller 6 photo picture pack, which gives you bigger pictures etc too and is pretty good value for money. Make sure your first picture is an overview of the whole item - this is what people will see in search results and lures them into the item.
my next tip: listing formats. Auctions are the simplist, people bid and you get a set amount, but the first thing to consider there is do you want to limit the minimum bid? if so, reserve or starting price?
When I search for items, I often choose the setting "lowest price first (Price & P+P)" - so the cheapest things come up first. however people equally choose ending soonest, or located closest, or best match. Whether you set a higher starting price or use a reserve is your choice, but dont use both! if you set your starting price as £50 and a reserve as £100, you wont sell it below 100 and will have to pay however much in fees on the starting price too. if you set it as £0.99, you will get the same price back but will save a couple of quid on the listing fees. so dont use both together!
Adding a Buy It Now (BIN) to auction listings is also great. I always thing its best to add the BIN about £5-£10 above what the item currently sells for, so someone who is impatient will use it and you will get a little extra money, whilst they get the item a week earlier. great little trick and only costs you 25p!
Your other option, is fixed price. In all honesty as a private seller, if I sell as fixed price I ALWAYS use best offer. Set your price a little higher than you want, set the decline threshold as your absolute lowest price you will take and your accept at the price you ideally want. Then you can consider an offer of a price between them, and it wont cost you any more than a normal BIN listing. Obviously not many people will take the full price then (Although someone did with me for £180 last week) so maybe set it a little higher than you are expecting, so they will offer the price you want.
finally we have duration and postage. duration assumes its an auction, for BIN I'd always choose 30 days. If you have a rare item, set it for a 10 day listing so it has maximum exposure to as many people as possible, but if you have the latest DVD that only came out the day before, you might as well do a one day listing because there will be 200 other copies up, and no one will even look at it until the last few hours. Simply use your judgment, and look at how many other of that item are currently for sale. As for postage, do your research! A lot of items you may think cant be posted can be very easily. Just weigh the item, find the dimensions of it and then add about 5-10cm each side for packaging, then use whatever postage option you choose and find out how much it will accurately cost. Work out the price for the packaging too, and mention that P+P charges include packaging (many sellers don't realize that, and it could lose you a star on your DSR's) - less postage means they will have more money to bid on the actual item. Also, whenever possible offer collection, and for very heavy items give the buyer an option to organize their own courier, and give them the details they need. I've bought things recently that I could walk to pick the up, you never know where potential buyers may live.
If you follow all these tips, you will probably spend another 10-15 minutes per item when you are listing them, but you will see how easily it pays off when they sell. Try it for your next few listings, and see how much it helps!
I hope my guide has helped you earn more money from that random thing you just found in your basement/garage/whatever.