Ready to bring the artist out in you!
When you are working with a stretchy curve on a garment, especially a neckline, it is very important to stay-stitch the seam allowance as soon as possible when you begin handling the pieces. Set your stitch length to a shorter stitch than you are using for construction - quilters would recognize a 2.0 length, and stitch 1/8" inside the seam line (1/2" from the raw edge) on all inside neckline curves. Then carefully clip the seam allowance every 1/2" - 3/4" up to, but not through, the stay-stitching.
Generally, it is fairly easy to make a skirt from neckties. It is my preference to make sure all the ties I use are the same shape, so I use the narrowest I plan to use as a template to trim all the others. You can make silk ties easier to manage if you fuse a 1/2" wide strip of lightweight fusible interfacing over the seam lines. Cut enough strips all the same length so all your ties end up the same length after trimming.