NOTE: This is the "all purpose" flour mix I've been using lately, with really good results.
Cybele Pascal's Basic Gluten-Free Flour Mix
4 cups superfine brown rice flour
1 1/3 cups potato starch (not flour)
2/3 cup tapioca starch
Combine all ingredients in a large zipper-top bag. Shake until well blended. Source: The Allergen-Free Baker's Handbook by Cybele Pascal