Find a dress and matching fringe trim suitable for sewing. Woven, as opposed to knit, dresses are better suited for sewing on embellishments. Flappers commonly wore dresses with drop waists and shorter hems that ended above the knees. If you cannot find a drop-waist dress, a shift dress works as well for the boyish flapper look.
Decide on the location of the fringe. You can sew layers of fringe from below the waist all the way to the hem, or add even more layers starting around the bust. Fringe can be expensive, so to save money, you can sew just a few layers at the very bottom. Measure around the circumference of the dress at the location of each layer, and cut the fringe. If using a knit dress, add several inches to the length of each layer to account for fabric stretch. Pin each length of fringe onto the dress.
Thread a sewing machine with matching thread, and sew on each layer of fringe.