Scalloping looks daunting.
Hella pretty, but so daunting. Right?
It's actually really not that difficult to accomplish
All you need is paper and pen, some writing implement that won't stain your fabric (tailor's chalk, chako pen, fabric marker etc.) a round object like the bottom of a bottle or bowl, a bottle cap, the base of a spool of thread--depending on the size of your desired scallop (and of course, if you have a French Curve that's ideal, but tracing a round object is a bit more accessible) and last of all you need a sewing machine.
Use your French Curve or round object to make yourself a paper template. If you are altering a preexisting garment, you'll want to add a strip of fabric rather than folding the hem. This way, you avoid shortening the length of your garment. If you are altering a pattern, simply lengthen your pattern's hem. Whichever method you choose, be sure that fabric is arranged with right sides together.
Lay your template with the curved edges at the bottom of your hem and trace all the way around.
Stitch over the lines using a smaller stitch length than you would usually. I use 1.8 generally. It makes easing around the curves oh so much easier. At the point between scallops, left the presser foot (making sure the needle is down) and reposition the fabric so that your scallops are crisp and defined. Trim around your stitching leaving about 1/8 allowance.
Now turn your scalloping right side out. It'll look a little messy, and the scallops won't be rounded. Don't worry, use a point turner or other implement to push your scallops into their rounded positing. Be sure to iron them flat.
Your last task is to use a straight stitch (at a normal length) to stitch around the open edge of your scallops. If you would prefer to avoid this seam--though I think it's pretty--you can serge the upper edge of your scallop panel rather than folding it, which will leave you with a finished edge that you don't need to address.
You're not just limited to hems.
Check out the collar!