1. Be emotional. Most good songs are written during emotional periods. Whether you happen to be sad, or happy, or apathetic (that's an emotion, too), incorporate. Sometimes everything is best expressed through music, and that's the best way to write it: for expression.
 
2. Be real. Don't fake it. It's really hard to write a good ol' depressing break up song if you're on cloud 9 after an amazing first date, and it's really hard to write about how happy you are while you're sobbing into a pillow, and it's harder to write about either of those when you feel absolutely nothing 'cause you just got off you're cycle and are simply exhausted and don't care about anything.
 
3. Make it your own. Not every line has to rhyme, or even have music. Sing, or rap, or just talk with guitar or piano in the back ground. Develop your own style with practice, because if it's not natural, it's not you. And if it's not you, there's no connection. It's just possible pretty music that you can't connect to. Every song, every poem, every word you ever write should have a piece of yourself locked into it. That's what makes music beautiful: the pain, the joy, the soul contained in every line.