What should every person do before becoming a songwriter?
Depends on what type of songwriter. If you want to be a typical songwriter that writes for a band, then know how to play guitar or piano or something like that and learn about poetry. It sounds dumb but poetry is the essence of lyrical songwriting. Now if you want to compose for an orchestra or a symphonic band, then at least play an instrument from one of the two, learn music theory, learn how to conduct, and learn the C scale chords. Most music is based off of that specific chord.