Alyson B. Stanfield's website http://artbizcoach.com/ is a goldmine of info. Her latest blog post http://www.artbizblog.com/ is on art auctions.
Artists receive frequent requests for donations. I only donate to causes that are important to me. While I prefer "artist friendly"* auctions I do donate to others, such as a recent one for a women's shelter, and of course to raise money for friends who are facing difficulties. .
* Artist friendly: reserve bid, promo for the artist, portion, at least 50% of the sale goes to artist.
auction for a cause near and dear to me, the Jack Millikin Centre.