I posted this for somebody else the other day:
My tips for getting the best prices possible:
Clear photographs, nicely presented (good background and lighting). I crop my photos and reduce the file size so that the auctions don't take too long to load on dial up connections. However, this is only really an issue as I often add 5+ pics to to an auction.
I use Auctiva - then you can add lots of photos for no extra charge. You can also schedule auctions for free.
I list all week, and schedule auctions to start on a Thursday for 10 days. Then you get two weekends of potential viewers.
Add as much detail as possible about condition and flaws. I also say that if the buyer finds a mark or something that I haven't mentioned, then I will happily refund once the item has been returned.
Add that you are a pet/smoke free household if you are, and that all items will be freshly washed prior to sending.
Add a link to 'sellers other items' people often bid on a few things.
Offer collection in person as an option (don't accept Paypal for this though as it leaves you open to scams), and a reduction in P&P for multiple wins. You save 20p on all subsequent items if winning bidders pay in one transaction, so it's worth trying to get them to bid on a few things.
Make sure your P&P is reasonable. I would say an absolute max of £1 above the actual cost of stamps. Less if you are not using professional mailing bags (I buy these from Ebay), and posting promptly. I say that I will post the same day if payment is made before 12pm, so often make a few trips to the PO per lot of auctions ending. Hence the P&P charge is more than the cost of the stamps and packaging only.