When I am using my walking foot I let it do all the work, don't pull on the fabric, just guide it. I use a longer stitch length and don't drop the feed dogs, and just stitch away, removing pins as necessary. This may not be the right way, but works for me. I use a lot of flannel and always use a cotton batting. I don't like the polyesters any more. They tend to creep through the fabric over time and are just hard to work with. Bamboo batting works well too.