Far too many sellers lists clothes without measurements! This is the top no, no.
For instance. Whilst searching for a particular item in a size 20, the chest measurements ranged from 48 inches all the way up to 56 inches! Different manufacturers use different sizes. You'll have far less negative and neutral feedback, complaints and refunds than if you'd simply listed the items measurements. You'll sell quicker, get more bidders and often make much more money!
It doesn't take long to measure clothes. Must's are chest, waist, inside leg, hips and the length.
It will also save you replying to questions about measurements and you'll make your customers happy! It's so frustrating when there are no sizes, you love an item you've just seen and there's 2 mins before the auction finishes. ARGH!
Another no, no is to not use a BIN. I personally don't want to wait for up to ten days to try and win an item and possibly have no chance of getting it, especially when newbies don't realise it's ridiculous to keep bidding days before it ends. If I love something and want something, I want it there and then. A lot of the time I don't even look at auctions, just the BIN's (you may even make more than you thought it would go for if you use a BIN, but be sensible in your pricing!).
Also don't be silly with postage charges, it puts people off BIG TIME!
Why do so many people sell clothes that are really bobbly and past their sell by date??! It's incredibly frustrating for a buyer to receive items that should have been thrown away a long time ago. Think before you sell, would you like to receive a bobbly/dirty/old/well worn item? No? Well, neither do we!