use bcy-ml6, or textite w/ silicon, or some other type w/ silicon. put it on gently, let it sit overnight, wipe off any excess gently. each strand of your string is made of a million tiny strands, and too much friction can damage some of the fibers and make them fuzz up.

some guys will use a hair dryer to melt it on. theoretically, when the wax gets hot and melts - it will run away from tension (the inside of the string), so i wouldn't advise doing it that way.