Check that the chorus has a good hook. This is the part of a song that most people remember. If the chorus is weak, then even if the rest of the song is very good, it will probably be forgotten. A mediocre chorus can often become a good chorus just by slightly changing a line.
Create an interesting beginning with something that will instantly engage the listener. This could consist of, for example, a soft beginning which explodes into life, a spoken vocal, or intriguing lyrics. These are all tricks which will help keep a listener interested.
Adjust the tempo of the song slightly. This may be all the song needs. Compose different versions, with tempo changes in different parts of the song.
Make a basic recording of your song. This only needs to be done with a vocal accompanied by an acoustic guitar or keyboard. Making a recording of good quality is not important, as you will only be listening for ways of improving the song, not the quality of the production.