There are many ways to lace a corset; one is the "rabbit ears" method shown here. Notice how you can't see any ends to the laces. This method uses just one length of ribbon. I started at the top. Laced down to the waist, where I skipped a grommet - leaving a "loop" of ribbon at each side before continuing to lace down to the bottom.
At the bottom I knotted the ends of the ribbon together and tucked the knot behind the grommet on the bottom left.