pinch a string in between your fingertips as hard as you can, and then have a friend yank it as fast as (s)he can. Learn it the old school way
As the other two have succinctly said, avoid friction burns. Tennis strings have friction due to tension --> (mains) resisting movement (crosses). If you pull the cross strings across the mains quickly enough, the mains will pit and have burned (melted) pits from the friction created by the crosses.