Be brief, but be enthusiastic and positive. Ooze excitement without sounding grandstand.
Herald your auction and list its unique characteristics. Anything special, for example a pack of 20 Forestmen or a Galaxy Explorer, should be listed on the first screenful. Come out swinging, but don't be giddy or presumptuous.
Put the rules down at the bottom -- people won't read them until they've decided that you have something worth buying. No sense making everyone wade through the procedural rigamarole.
As near to the top as possible, list a summary of everything to bid on. Don't go into detail here -- as in the teaser, you just want to give an overview. Be hierarchical if you have more than 50 items for sale.
If you are conducting a multi-phase auction with many announcement postings, try to give a sense for where you're going over the coming days or weeks as you put up more and more items for sale. (Hopefully you have planned your phases.)
8 Jan 96 [TSL]