Here's how to do it. First, select the T-shirts you want to use. Roughly cut out the logo or picture you want to feature. Leave lots of space around the logo... a couple of inches if possible. You will be trimming it later.
(OK this isn't really a T-Shirt. Just go along with it!)
Cut medium weight fusible interfacing to fit the back of the T-Shirt. This will help stablize and reinforce the jersey fabric.
Iron the interface on the back of the T-shirt according to manufacturer's instructions. (I never really follow those instructions. I just turn on my iron and do it. That's why I am wayward.)
Now is the time to trim the piece to the size and shape that you want. Leave at least a 1 inch fabric around the logo. Try to keep the about the same margin on all of your squares for a more uniform look.
Some people choose to have all squares the same size. I am not one of those people.
Some of the logos that I selected were embroidered designs off the front of polo shirts. This was a great use for nice, but stained fav polos.
Then, select your border fabric. Again, you might want to use the same fabric for every block. I decided to use fabric that complemented each design. Cut strips of fabric to the desired width. I sewed each side border first and then the top and bottom. Iron the seam allowance toward the border fabric.
I am going to use a white on white fabric as lattice work. I will be using a bandana print for the back because Ben loves bandanas almost as much as T-shirts. I might use old ties in the lattice work, too. That will be another post if I do.
Here are my all my blocks together and a pictorial history of my husband's adulthood: