I love making flannel quilts.
I prewash all flannel and dry on high heat and immediately remove and fold it smoothly - no wrinkles.
I don't iron it - afraid of stretching it. Because I remove it quickly from the dryer there's no need for ironing.
Last quilt I made I did not use pins because the fabric did not slide around. I just "pinched" the middle of each block to keep it lined up.
Very important to remember - clean your bobbin area everytime you refill the bobbin. Flannel is very linty!]
I used 3 layers of flannel - top, batting and backing.
I would not recommend an "intricate" pattern using flannel. It's very stretchy and frays easily. Simple is better.
I just use a very simple quilting design. Last quilt, I just quilted from one corner of a block to another corner of a block beneath it creating a "diamond" design. Thing giant zig zag across the quilt with another zig zag crossing over it in the center of each block.
Those of you with sergers - dust them off and use them. Sergers are fantastic for flannel quilts.