You can really only learn to write songs by practicing writing songs and working on your theory. You'll learn what works well with what after time. Teachers can only expedite this process.
About developing your style, that just comes with time. You'll play thousands of licks; the ones you like will stick with you, the ones you don't will get removed from your repetoire...
"You must stab him in the heart with the Bone Saber of Zumacalis... well, you could stab him in the head or the lungs, too... and the saber, it probably doesn't have to be bone, just anything sharp lying around the house... you could poke him with a pillow and kill him."
- Aqua Teen Hunger Force, The Universal Re-Monster
- Aqua Teen Hunger Force, The Universal Re-Monster