Cut the tee shirts extra big first. I cut mine at the shoulders and then the side seams. Then securely fuse interfacting on the back. I prefer a lightweight pelon. You can use a fusible tricot knit interfacing if you want to. The tee shirt knit runs up and down. Place the tricot knit crosswise so the block doesn't stretch. Then and only then, cut the blocks the size you want them to be. Now they are ready to sew. You can put them together with a sashing or just sew them together. You can really use your imagination. You can also add patches like scouting patches or school patches. I sew on lots of things as long as they are washable. I prefer to machine quilt a tee shirt quilt. The fabric is too stretchy for hand quilting.