Okaaay .... deep breath...
Here are my suggestions - I don't sell very often, these days, but I do buy regularly.
Use lots of photos, and take accurate measurements of the items. I've passed on lots of listings because I've no idea what 'medium size' really is!
:dull:
Take a minute to decide how to photograph your item - a crumpled shirt chucked on to an unmade bed [eeww!] won't sell. When I sell, I photograph my items on a crisp white tablecloth with a small bunch of fresh flowers laid next to them, because it looks attractive and gives an instant size comparison. Oh - and check the background in the photos in case you've inadvertently included last night's takeaway pizza box or a mountain of ironing!
Present as much information as you can, and invite questions from potential bidders. Avoid woolly descriptions - a 'leather-like, Gucci-style' handbag isn't leather. Or Gucci. And will earn you a rap over the knuckles because using posh brand names to describe something else is not allowed!
Don't add that line that goes something like 'check out my other items for Prada, Stella McCartney, Cartier, Mont Blanc, Hermes, Tiffany ...' unless you're actually selling them. eBay's finally clamped down on this as it's keyword spamming, trying to encourage more people to view an item on a false promise.
If you can only post on Tuesdays, or you won't accept returns, or you'll only accept bids from UK buyers, say so in the listing.
You'll still get people telling you to only post on a Thursday at noon, when there's an 'r' in the month, and the moon's in Scorpio, so they'll be at home to take the parcel, but you can forestall the idiots a bit.
To get the best price for your items, time your listing so it'll finish on Sunday evening when lots of people are online.
Pack your items securely in clean wrapping, so they don't get damaged by butter-fingered postmen in football boots. Including a short personal note thanking the buyer is a nice touch.
Post promptly, using signed-for delivery, because there are people out there who'll try it on and claim they've never received their parcel.
Keep the lines of communication open with your buyers. Don't pester for feedback. [This bugs the hell out of me!]
Oh - and there's a message board and forums in the 'Community' section where you can get lots of help and advice, well, as long as you ignore the trolls, that is. :sad:
It's worth casting an eye over any threads naming and shaming problem buyers and adding them to your 'blocked bidders' list, so they can't wreak havoc.
Phew. Good luck! :up: