I just finished one for my sister using her deceased hubby's shirts, pants, jackets, jammies, robes, etc. I cut all my squares at 12" and didn't use sashing (sashing is fine for lots of people, just not me). Try to get a lot of variety in the shirts/clothing, adding in cuffs, buttons, collars so you can use for a 3-D look. Put an iron-on stabilizer on the back of all fabric pieces, then trim to size..... to eliminate stretch of knits, a light weight is better and softer. Press your seams open to eliminate extra bulk at intersections. FMQ can be a bit tricky because of the extra thickness. I opted for straight line quilting using the walking foot ....there are lots of quilting designs that you can do with the walking foot. I use a light weight poly batting...no shrinkage to distort the images on the shirts.