This 1958 SI infographic breaks down the perfect free throw technique, as modeled by the Celtics' Bill Sharman.
Back in the 1950's, future Hall of Famer Bill Sharman was the NBA's reigning free throw king. The Celtics guard led the league seven times in free throw percentage, averaging 88.3 for his 11-year career. In 1958, writer Jeremiah Tax and artist Ed Vebell examined his "impeccable style" for this SI infographic. It's all in the waggle, as you can see below: