Step 1. Try on your dress inside out and determine how much you need to take in at the back, and pin. It's kind of hard doing this on your own, so I'd suggest the help of a friend, or doing it on a dress form. Lay your dress flat, lining up the waistband, hem, and neckline, and pin down the entire dress. Sew with a straight stitch from neckline to hemline, as seen below.