I tie mine on using a constrictor knot just like Ryan Sanpei's video. I have found I can get it much tighter if somebody helps hold everything in place. On some of the newer high performance materials, especially if the string is made under high tension, you cannot pull the knot tight enough to get it to bite. In this case tie a permanent knocking point in the string just below where you whiskers will tie on, above on the bottom one. Then when they slide the knots will bump together and effectively keep them in place.