Write a blog entry imagining that you are either a boy who has just broken up with his girlfriend or that you are a girl who has just broken up with her boyfriend. Maybe try both. How different are the entries? Can you hear the voices of your characters as you get under their skin and make them vivid and real?
Trying to get into the head of your character will help you as you work on stories of your own. Characters that ring true are essential for good writing and the best way to get good at writing characters is to practice.