If you're selling and just having a clear out i would recommend making a normal 7 day auction, ensure you put the item in the right catagories (it'll guarentee people can find it)
I put my listing title in capitals and use lots of exclamation marks, try and put as much detail in the title as possible, like the brand colour and condition, it'll grab attention.
For you're description i'd making it large writting and i always use a bright but readable colour, really "big up" the item but dont lie, so if you're selling jewellry for example you might go on about how beautiful and delicate the item is, well made and put a good description in, it doesnt have to be long though, and i usually add a little bit at the end like "great for a birthday or special gift, happy bidding"
Id also make sure you fill out all the little drop down stuff as well as again it makes it so much easier for buyers and TBH i'm out off if i cannot see the condition and stuff from the top bit.
Make sure you add a picture, and the picture shows the item clearly, and i would also say its worth paying the extra 10/15p for a gallery pic, the insertion fee is only 25p over all so i dont find my ebay fee's are too big.
Try and make you're postage cost as accurate as possible but also factor in packaging costs. I always offer second class postage too and it doesnt cost extra to offer it.
Most importantly dont start you're off with a high openning bid!! My friend simply cannot get her head around this and starts them at what she wants for it, if it's a high priced item use the reserve feature.
I recently put some perfume on, started bidding at £5 and it went for £30, for most other things i start at 99p and i found selling tongue bars they didnt sell when i started it at 99p but sold for £5 when i started it at 1p.
If you're only selling to make a little bit of extra cash and the items arnt valuable i'd start low cos people WILL bid it up.
anyway, thats my massive long post about ebay lol!!! Hope it helps.