I have made a couple of commissioned T-shirt quilts. Once you have all of them together, figure out how many of them can be cut with the same dimensions - or at least the same height or width. If there is something really special that you want to be the focus - pick it! and center it in your design. Then you need graph paper to figure out what size you want the finished product to be. Draw in those that you have settled on a size for and don't forget the seam allowances that will be lost. I try to use those same size blocks in the center, either horizontally or vertically. Then looking at the designs of the others, try to keep cut sizes as close to the same as possible. I put everything together with sashing strips which will cut down on stretch in the long run. Both of mine came out in three vertical rows and the sashing pulled them together whether they were the same widths or heights or not. I'm sure there are others out there who have more experience with this. I did not use any stabilizer, and I know that one of them is still used every night at least ten years later. Good luck with your labor of love!