I have made many memory quilts using all type of clothing. After I cut away the shirt backs, I use a lightweight fusible interfacing to back the area that will be cut into a block. I also use graph paper to map out my design and block placement. I try to distribute dark colors, whites, etc. And I like to vary the block sizes a bit to add interest and I usually add sashings. But, whatever you do it will be an amazing keepsake for your friend. Have the tissues ready! Good luck!