When I was asked to do a t-shirt quilt for a friend's daughter, I went looking for help. I found this website (I found very helpful):
https://www.youtube.com/watch?v=fW6v...id=IHzyAEhSiXU. I aslo found graph paper helpful for the layout.
One thing my long armer said was to not use a 45 degree angle if you are using a sashing strip. It stretches to much and will be hard to quilt on a long arm.
Have fun and let us see the quilt when you are done.