Extending range for male voice?

hm. so I'm 16, I'm a tenor and I can sing up to about an E comfortably. I would like to be able to sing a bit higher. How can I accomplish this? Does it have anything to do with blending falsetto or head voice with chest voice and whatnot? If so, how do I do this? I know some people say you have to wait till you mature, but I have a friend who used to have the same range as I do, but now he's up to an A. He said something about blending the head voice or whatevs... Anyway! Any tips, comments would be appreciated mucho. thanks :D