Tips:
2 mm or larger cord works best. Otherwise the knots are small and more difficult to work with.
If you're going to be tying more than a few knots, fortify the ends of the cords with Super Glue or tape. It will make it easier to thread the cord through the loops.
To secure knot ends, singe the ends with a flame for nylon cord or use a drop of Super Glue or GS Hypc Cement.
To hide cord ends, use a needle to thread the ends down through the knots. Use a yarn needle with a large eye and a rounded point (a needle with a sharp point will poke into the knots and make it impossible to get the cord where you want it).