Circle skirts have curved hems that can be awkward to turn up. One way to deal with the curve is to hem with bias strips cut from the same fabric. Because bias strips have some give, you can stretch out the lower side as you sew it to the dress, then neatly turn under the top side and not have a bunch of little pleats of excess fabric to deal with.
For this dress in semi-sheer cotton, I cut a bias strip two inches wide, and sewed it to the bottom of the dress, right sides together, using a half-inch seam. Then I turned it up under the skirt and neatly pressed it, and then folded in and pressed the other raw edge.
That edge can be machine-sewn in place, or hand-sewn, if there's time to kill, and that circle skirt will be nicely hemmed, with a nice hang.