I've been playing guitar for 5 years but never really practiced seriously. My technique is average (I guess I could play most stuff by Metallica. Don't know about the solos.) but I do not know any songs. I want to improve my techniques but I feel like playing exercices (lately being Petrucci's chromatic exercice) does not get me anywhere. I also greatly need to work on my rhythm. What songs should I play?
trust me when i say:

metallicas solos arent hard...(except possibly blackened could be a bit hard)

I would say try to play a Metallica solo