For me rule nuber one is inspiration.
By that I mean I listen to a lot of various music all the time and I pick the approaches I like. Of course I mostly listen to music I do like, but genres vary greatly, even nationalities. I also sometimes listen to things I don't like that much and I try to find out why exactly is that so I can avoid it.
When making a song, I often utilize something I liked somewhere, either knowingly or subconsciously. The music of the whole romaticism era was based on that idea.. People like Dvorak or Smetana, even Mozart and countless others utilized folk tunes for their composition.
You can do very fine with the simplest 12 bar blues or 3 chord (and the truth
) country for all your musical life, if that's your thing, many good performers did.
It is like vocabulary, I don't make words up, even phrases, but the song should be original and from the heart as a whole, not note by note. I heard very famous artists say the same thing many times..
Giorgio Vasari in his
Lives of the Most Excellent Painters, Sculptors, and Architects advises to pick a master and basically copy him until you are advanced enough to come up with your own style.
Tommy Emmanuel very often talks of "stealing" his licks from Chet Atkins and how he hopes other people will steal things from him and then somebody steals it from them.
and here are some famous film directors, Jim Jarmush and Godard
“Nothing is original. Steal from anywhere that resonates with inspiration or fuels your imagination. Devour old films, new films, music, books, paintings, photographs, poems, dreams, random conversations, architecture, bridges, street signs, trees, clouds, bodies of water, light and shadows. Select only things to steal from that speak directly to your soul. If you do this, your work (and theft) will be authentic. Authenticity is invaluable; originality is non-existent. And don’t bother concealing your thievery - celebrate it if you feel like it. In any case, always remember what Jean-Luc Godard said: “It’s not where you take things from - it’s where you take them to."