Assistance with Usability Guidelines for User Account Design

Hello,

I was hoping for some assitance with usability guidelines when designing a user account section of a site. I work for an auction site that is a little like eBay but deals with much larger and expensive items.

I wasn't able to locate information or other resources on the subject but as a start to my research, I looking at sites such as eBay and Amazon.

Thanks

Ally