How does one avoiding losing their shirts with auctions houses?

[Topnotchsy]

Thanks everyone for the replies.

I have sold cards on eBay myself and through PWCC, but at this point much of my collection is memorabilia and eBay is tricky for items like that. Auctions often don't get the eyeballs and BIN's can sit forever. (I know because I've been able to buy some really nice items on eBay for far below auction house prices...)

When it comes to selling at the auction houses it sounds like the key thing is to negotiate in advance, particularly if an item is in high demand and/or does not require much work (it is already authenticated and is a relatively standard item...)

Can someone explain (or point me in the direction) of what a resale permit is? Is it something that as a collector who also sometimes sells items can reasonably get? If I understood correctly resellers don't pay sales tax. Is that correct?

Thanks