I turned the t-shirt wrong side out and pinned. You'll notice the pin in the middle. That is where I cut the length to use for my ruffles.
Now, take the excess fabric and cut into strips. Mine was only wide enough to cut into 2 strips.
Sew along the side seams on your shirt where you pinned. Cut off excess fabric, leaving about 3/8" seam allowance. Again, I just eyeballed it!
Next, sew all your strips together, end to end, until you have a lone strip. Make sure the seams are all on the same side (trust me on this one!). To ruffle the strip is very easy. Set your machine to the longest stitch and tightest tension. I stitched mine strip down the center so it ruffled on both sides. Then let the machine do it's magic!
You are done! This is how mine turned out and I love it! I get so many compliments on it!