I have found the EBay workshops given periododically has helped me quite abit. They have all of the previous workshops archived and be found by clicking on the sitemap, look under news then workshop calendar link. They have many subjects there not just about EBay but for Businesses in general.
I also took an EBay university class at my local College which was very informative. Again look at the sitemap under Help - Resources - eBay University. They also have online versions and CD versions available.