--1 yard fabric (I used an unworn blouse I had on hand to coordinate with my dress. This technique works really well with contrasting colors...like white sleeves on a black dress)
2. Position your fabric under the sleeve line of the dress. Keep the rectangle perpendicular to the dress to create the right drape.
3. When you have the sleeve fabric positioned where you want, pin into place along sleeve line. You will be leaving 3-4 inches beneath the armpit unpinned for now.
4. Top-stitch close to dress edge to attach sleeve, leaving armpit fabric free.
5. Flip dress to inside and trim away excess sleeve fabric, then trim sleeve fabric from bottom sleeve edge up at an angle to where sleeve fabric meets armpit of dress. Make sure to leave at least 1/4 inch extra to have fabric for seam allowance.
6. Stitch underarm seam on sleeve and hem.
7. From inside of dress with right sides together, stitch up the open 3-4 inches close to dress sleeve edge. Press.