1. Cut the shirt along the side seams through the sleeves to open up the sides.
2. Reusing the neckline is a little tricky, and you might have to play with it. Fold the shirt at center front and line up the pattern on the fold. Line up the neckline as closely to the pattern as you can. The pattern I used was not a v-neck, but I could still line it up with the curve.
3. The back neckline of adult shirts is usually a pretty shallow curve, so I just stretch the neckline a bit to make it work. Line up the center back of the pattern along the fold of the shirt.
4. Cut out the sleeves. I did reuse the hems on the sleeve when I cut them out. See how I drew on the hem allowance? I did not eliminate it when I cut out the sleeves which resulted in my sleeves being slightly longer than the pattern’s length.