The first president to make effective use of television (in the first televised presidential debates, in his visual appeal, in his use of the first presidential press conferences to be televised live on national tv) was

John F Kennedy

Kennedy understood and used the power of the television for political gain.

Kennedy was an attractive and dynamic president who used the television to connect to the citizens of the US. Kennedy and Nixon debated on television which provided Kennedy with a large captive audience. Kennedy used the television through his presidency and even the events of his death were televised.