You know how when you find a song you really really like, you tend to listen to it on repeat until you hate it? The same phenomenon can happen when it comes to your own music.
After you produce a great song and hear it for the first time, you may be thinking you've struck gold. But then when it comes time to promote your music, you get so used to the track that you can tend to forget how great it sounded the first time you heard it. Even by the time the mastering is done, think about how many times you've practiced it and listened to it just to get to that point.
This is a trap that sometimes causes artists to want to move on to the next project too quickly. When it comes to your song promotion, you need to remember that anyone who you are trying to reach will be hearing your track for the first time. You want them to have the same reaction you did when you heard it for the first time. The song may have grown old on you, but you need to bring it to the market as if its the first time you ever heard it.
If you have a hit song when you first hear it. It will be a hit song when others first hear it. If people have never heard it, it's new to them.