I agree with Kathy, rules are mostly opinions. But there are a few tests you may want to take before you cut everything up and sew it all together. Defnitely wash the flannels. They don't shrink even. You might want to try the minky out on a small piece to see if it "rags". I think all cotton fabrics are so much easier to handle and sew. I've never made a rag quilt, but I have friends who say the rag scissors make the process easier. Just do your testing and Happy Sewing!