Welcome to the QB from SE Michigan! I have only made one TShirt quilt and it came out ok. I took over making it after someone else cut the tshirts not leaving a seam allowance. This made it more than tricky. First thing it to be sure you have some kind of fused under facing that will help keep your blocks close to square. I see that many here have already given you the soundest advice on making a tshirt quilt so you are in great hands. Just keep on jumping in we love to have you here. Again welcome to the QB.