From “The Essential Secrets of Songwriting” website:
For your song to be successful, it needs to capture the listeners’ attention right away, and really make an impact. If it doesn’t, it won’t sell, and it’s as simple as that.
There are three aspects of a song that rise above the others in importance: the melody, chord progression and lyrics. So once you’ve written your song, give it the once-over with this checklist:
1- Is the melody memorable? (Melodies that leap high and low somewhat randomly and seem to have no noticeable contour will be hard for the listener to remember. A melodic hook can really make a melody stand out.)
2- Are the chords predictable enough without being boring or repetitious? (Songs with too many of the same chords, or too many chords, both cause the listener to become bored.)
3) Do the lyrics relate to experiences and emotions that the average person encounters in their life? (If it’s just a song about how you feel, with no accompanying story line, don’t expect the listener to relate to it. A song will appeal to people because they can imagine themselves singing it.)
Remember, when you write a song, you’re setting life to music. And you’re doing it as a representative of everyone who will listen to it. If it isn’t grabbing the audience on its first listen, go back and fix it. The world of songwriting is very much a “first impressions” world.