I prewash all my fabrics then heavily starch and press before cutting. Once a quilt is finished I throw it in the wash on gentle (I have a front load machine) and dry on medium. I wash the finished quilt because of all the starch. It's not very cuddly when it's stiff as cardboard. :)
I recently finished a quilt that I used flannel as a backing on. This was my first and last time using flannel. I washed and dried the flannel twice before using it. It still bled through the quilt stitching on the top in some white areas. I was very disappointed. Maybe it was because it was red, or maybe low quality flannel (I bought it from fabric.com), but either way it left a bad taste in my mouth for flannel.