The first thing you must work on is your voice.  The voice is a powerful flirting device. If used properly, you can sway many women with just how you sound. Make sure you have a full sound; no scratchiness.  Try to speak in a lower range.  You can practice this by laying flat... 

Breaking up with a girl is difficult but no matter what reason you have to end the relationship, at the end of the day, it has to happen. First off, you have to realize that there is only one way to break up with her, in person. It helps to think of girlfriends as just best friends...