Look for artists who are willing to donate art. Let them know that art auctions give them a chance to receive free publicity, and disclose how you plan to promote the event.
Help the artists choose a minimum bid for their work. You will want to convince the artist to keep the price in a reasonable range in order to prevent scaring off potential buyers.
Make sure the venue you choose is spacious. It will need enough wall space to display the different pieces of art. Use lights and backgrounds to highlight the works.
Put together a program that gives the artists' biographies as well as information about the works up for auction.
Hire a personable and experienced auctioneer who is knowledgeable about art. You want the buyers to be entertained as they bid on the pieces. If they are in a good mood, they are more likely to spend more money.
Provide notes to the auctioneer on the artwork being sold. The emcee should be able to provide a detailed description to the potential buyers.