Found this on QB:
http://www.quiltingboard.com/picture...s-t153884.html
This shows how to cut up shirts, plus provides asnowball pattern for a 7-shirt quilt:
http://thethriftyquilter.blogspot.co...e-thrifty.html
For flannel I would first cut the shirts apart, then starch heavily to make the flannel stable to work with. My method is to mix a 1:1 solution of Sta-Flo liquid laundry starch and water, "paint" this solution onto flannel fabric using a large wall painting brush, wait a couple of minutes to make sure fibers have absorbed starch, toss in dryer, then iron with steam. My kitchen island is a good place to do this. After ironing the flannel is quite stiff, which makes it *much* easier to cut and piece accurately.