Step 2: Cutting the shirts
Look at your shirt and decide how much of the pattern you want on there. Most shirts are going to have the pattern centered on the front. Measure from the bottom of the neckline to where you want the bag to stop, be sure to stop about 4 inches from the bottom (if you are using a really small shirt, it's okay to have less than 4 inches at the bottom, just don't have less than 3.) Then measure between the shirt sleeves.
Here's where the newspaper comes in handy. From the newspaper, cut out a square in the measurements you just took. That will help you cut more quickly and easily, and keep all the squares uniform.
Cut off the strip at the bottom of the shirt that won't be part of the square you just measured. Make sure to cut it off so that when you are finished, it is still a circle of fabric. Then cut through one side of the circle so you end up with a long strip of fabric. When you do this to both shirts, you will have two long strips of fabric. (If you are confused, see picture.)
Lay the shirts out flat, pin the square to each shirt in turn, and cut through both layers of fabric (the front and back of the shirt.) When you are done, you will have four squares of t-shirt fabric!