As being a fairly new composer, I look at a couple things when I make music.
1. Will this song be enjoyable not just by me, but by almost ever non-hater who enjoys listening to music?
Some music isn't just enjoyed by the author. Putting my feet in a listener's shoes allows me to distinguish whether or not I have done a good job putting together a piece.
2. Composer or Listener?
As being both of the above, I find it quite hard to avoid mimicing somebody else's work. With severe concentration and overcoming a melody created, moulded, fashioned by another artist, It's possible to create your own piece of work