I recently hemmed my cousin's prom dress and thought to my self "this would be a valuable skill for young people to know how to do, especially if they don't have the money to hire a tailor." Since most of us don't have that special interlock machine that will finish the hem of the dress, I came up with a simple technique that looks pretty professional in the end.
Step 1: Fold under 1/8" further down from where your desired length would be. Pin to keep in place. Press (with med to low heat iron) a creaseon the fold of the hem.Step 2: Sew 1/8" closest to the folded edge. Taking out the pins as you go.
Step 3: CAREFULLY cut off the extra unneeded hem length with a sharp pair of sewing shears. Try to cut really close to your finished stitch line you just sewed, but try not to cut more than 1/16".
Step 4: Fold under about 1/8" to 1/4" pressing and pinning as you go, so that no raw edges are exposed.Step 5: Sew as close as you can (1/8") from the inside edge, so that you attach the rolled under edge to the inside of the dress.
If you would like to see more handmade or vintage products of mine, please feel free to check out my sproutsmaternity shop (for maternity, children and accessories) or my jnsweeney shop on etsy.com (for vintage items).