Most all purpose GF flour is a blend of several types - rice, cornstarch, tapioca are commonly used as well as others. There are many brands of premixed GF flour on the market. I prefer Bob's Red Mill, but also mix my own. It is helpful to invest in a few GF cookbooks. I like the GF Gourmet series by the late Bette Hagman, but there are many newer books out there. Also lots of information available on the internet.