This is what Sufjan Stevens said

Do you have any comments or suggestions for young up and coming songwriters?

For starters, throw away the chord books and the notations for Stairway to Heaven. Stop listening to music, especially anything recorded. Don’t use tradition tunings. When you break a string, leave it off, detune, write a song with the guitar upside-down. Don’t write anything in 4/4 or 6/8. Record something on a 4-track and play it backwards. Try to learn it this way. Don’t use C or G or A or D chords. Find chords that make your hands hurt. Find out how far your hands can stretch on the fretboard. Make up your own language and sing in that language. Don’t use vibrato. Sing the whole song in your head voice, in your falsetto. You should never be completely comfortable. You should always feel a little weird.