For an outside corner, serge one or two stitches past the end of the corner, raise presser foot, gently pull the thread tail off stitch finger. Turn the corner and put edge of fabric right up to the needles. Pull up on the threads above the tension to get rid of any "thread slack," lower the foot and serge the next side.///...The inside corner is stitched by straightening the corner. Make a 1/4 inch clip diagonally into the corner. Straighten the inside corner as you skim the fabric edge.