what kind of music do you like? If you like rock/metal you
should either learn to bass or drums since there are too many
guitarists out there already. If you like jazz, you should learn
piano, drums, saxaphone, or double bass. If you like classical,
piano, violin, cello, viola, clarinet or any other orchestral
instruments.
If you like pop, just learn to sing and play the acoustic
guitar.
