Timing is everything
Encourage bidding by promoting the practical elements of an online auction.
Notes from the Training Department: At a physical charity auction, patrons are influenced by environment, social/peer pressure, and often times - your selection of beverages. Online charity auctions are entirely different! You're competing with all other online retailers, and therefore should convey the message that your "store" is better because they're getting their necessary shopping done while also helping out a great cause.
Choose your time of year
Create an experience
Hold your online auction