If you plan to machine quilt, my best tip is to heavily starch the flannel backing before layering. This will stabilize the flannel so you don't get puckers and tucks. My method is to mix a 1:1 solution of Sta-Flo liquid laundry starch and water, "paint" this on with a large wall painting brush, wait a few minutes to make sure that the flannel absorbs the starch, toss in dryer, then iron with steam.