You want your story to be fresh and not something everyone else is writing. So many subjects have been over written and they do eventually become boring. Have a fresh outlook on the subject you are writing.
Make it interesting. Sally meets Joey and falls head over heels in love with him. Joey is more interested in Mary Ann, who is the bad girl. What can Sally do to make Joey notice her? Does she decide to be a bad girl or does she remain her sweet self? Maybe she can ignore him, but Joey's best friend, Mike, notices her. He may say something to Joey and then Joey wants to date her, but she ignores him.
So far, it's like every other story. How would you change it? How would you jazz it up? Can you find a way where Joey will fall for her, or does someone else come into the picture?
Think of all the books you have written lately, isn't that the premise for all of them? How are they different from the others? What makes them more interesting to read? Think about your book. Are you writing something different? Maybe a different time era, a different setting, different characters or maybe a whole new story about something little known to people today. You have to make your story different to make it stand out to an agent or publisher. Stretch your mind and see how you can do that.