I do a square knot. I don't wrap it twice each time, but that might make the knot more secure. Square knots don't slip like other knots seem to. But I do go ahead and clip the threads and tie them as I go, then trim to about 1/2 to 3/4 inch after the knot. I'm not sure that's better, it's just the way I started doing it and it's the way I feel most comfortable with.