What are the key elements to write a good song?
To answer your question(s) thoroughly nirvana, one would have to sit here & type all day but i could give you the basics so you can be on your way 😛 For someone to choose music for their song they will more often than not either use Trial & error (eg. play around for something they like) or take an already existant one & make it there own (eg. if a riff that someone REALLY liked was c,c,g,g,d,e,g#,f they could go something like c,g,c,g,g,g,d,d#,e,g,g#, f,f,f, or something to make it their own. Lyrics are a funny thing to play with, usually as a rule of thumb you should write about something that you know back-to-front. It makes it a whole lot easier for you to write & also more personal for the people that are listening to it.