Expose yourself to music at an early age. Paul McCartney's father, Jim, was a trumpet player, pianist and led a jazz band in the 1920s. When a song played on the radio, Jim would point out the instruments used to his son. He took Paul to concerts and, encouraging him to take up music, bought Paul his first instrument.
Take music lessons. Paul McCartney took lessons at the encouragement of his father, but he was actually more skilled at playing by ear.
Learn to play a vast array of instruments. Paul McCartney can play the trumpet, guitar, piano and many others. In his album titled "McCartney II," released in 1980, Paul played all of the instruments for every song, including synthesizers.
Allow everyday life to inspire you. Paul McCartney wrote his first song, "I Lost My Little Girl," at the age of 14, after he lost his mother suddenly to breast cancer. Paul's encounter with a vanishing man on a hill overlooking London inspired the lyrics to "The Fool on the Hill." The song "Driving Rain" is a result of a trip Paul took down Pacific Coast Highway in the rain with Heather Mills.
Collaborate with other brilliant musicians on some of your songs. Many of The Beatles songs were a joint effort between Paul McCartney and John Lennon. Typically, one of them would write the majority of a song and the other would provide input and minor revisions to perfect it.
Write songs for other musicians to expand your accreditation. Paul McCartney wrote for many other artists, including Peter & Gordon, whose career got a jump-start from the two hit songs Paul wrote for them.
Expand your horizons into other venues and genres. Paul McCartney published a book of poetry, "Blackbird Singing," in 2001. Obviously, he wrote rock and pop music, but he also wrote music for movies. He composed the entire soundtrack for the 1966 movie titled "The Family Way," and the title track for "Vanilla Sky," which was nominated for an Oscar. Additionally, Paul has composed numerous classical pieces.