If you are doing a dart in chiffon or lace the nicest finish is to bring up a length of bobbin thread and thread it backwards up to the top spool (do not just knot it and pull it backwards, that would put lint in your tension mechanism ) then sew the dart from the point to the seam......it looks like magic ..... always remember to sink your needle into the fabric where you want your first stitch to be every seam you start to sew.......yes I used to work for a designer and everything I worked on was an original for a special group of customers. circa 1957