The design will depend on the type of clothing -- men's dress shirts, plaid shirts, t-shirts, and you can include the pants, too. Then, do you want large pieces of the clothing, or do you want it cut up and made into quilt blocks. The links her are some good examples of square blocks of clothing with sashing. If you want to make quilt blocks, then choose a block or two. The pants might make good sashing. Since the clothes are probably part polyester, I'd probably use a polyester batting, probably light weight, although any weight would work.