It's a real problematic question. Some musicians, whose I know, do it on themselves - doesn't exist manual what describe method to write songs whats likes everybody. If someone writes something special you don't find out it, cause I like something else. For this opinion we have explanation, BUT.
How to make really interesting and good music what will to listen a lot of people in the world? Have a stamina and stay yourself.
In this world it isn't all if you like playing the any musical instrument, or can singing. You must to look good, have a correct contact or a daddy who has record company. I suppose you haven't, if you're reading this. I think that a lot of really good musicians aren't famous, although they have not things I described. That's sad.
For example, why do we put music to the genres? Mean human-played music. It would be better to dispense human-played music and music is made by computer or something like that.
I know lot of music groups, which are not dispense to the genres, you know.
I am for noncomercial music. Switch on radio, and hear some song what's about nothing. It's round around to repeat text and 3 chords (I like using this sentence :). Music could be something like book - have a story, what we try to spend or experience. And have a soul! Or, it does matter if you like listening mainly lyrics or a music...
So, my head burnt down from this written-consideration and hope, you'll like and think about it :)