I also make Tee Shirt quilts for customers. The biggest thing is Stabilize. It makes all the difference in the world. I have actually done a double sided Tee Shirt quilt with Harley Davidson quilts. It was amazing. I used Orange and black borders and it was one of my favorite quilts.
I do a lot of memory quilts, with baby clothes, a family member or loved one who passed away, I take the items and make it into a keepsake quilt. If you incorporate pictures into your memory quilts make sure to use really good quality photo fabric. The pictures last a lot longer with good quality. I tried doing it a lot of ways and really the best was start with the quality stuff.
As far as quilting goes you can do long arm, or stitch in the ditch with echo stitching
Eleanor Burns has a Tee Shirt quilt Video that is pretty informative. And if you want some ideas on the baby quilt keepsake send me a pm I can send you pictures. Baby Quilts are so fun to make. It is a totally different concept of quilting for sure.